Figuring out how much to tip service providers can be a tricky endeavor, fraught with a good share of mathematics and emotions.
You might slip the limo driver an extra $20 bill to show appreciation for a ride from the airport, or demonstrate utter distain for bad food and poor service at a restaurant by leaving two single pennies.
And it seems almost any establishment where coffee or pastries are served has a tip jar on the counter. Tips are the only thing that makes it economically worthwhile to deliver pizzas, and budgeting the tip into the cost of a drink when dealing with a bartender can be the best way to get good service in a crowded cafe.
"People tip to reward behavior," said April Masini, an etiquette expert based in Naples, Fla., who writes an advice column called 'Ask April.' "If you like the way your hairdresser or delivery boy treated you or the way he or she served you, giving a tip shows your gratitude.
"People also tip to encourage a relationship," she said. "Some people tip a gardener or a manicurist because they want to encourage good service with this particular person."
Then, there are fear-based tippers, she said. These people tip because "they're afraid (that) if they don't, the waiter will spit in their soup or that their date will think they're cheap or that the impression they're leaving will be less than they want it to be."
Stellar service or not, tips are more or less expected. Many service workers are paid minimum wage -- or less in the restaurant industry -- and they rely on tips to feed their families and put themselves through college.
But how much to tip is still up to the customer.
Servers at a sit-down restaurant who wait on diners hand and foot expect to receive a tip ranging from 15 percent to 20 percent of the meal's cost. For truly exceptional service, diners are generally expected to tip more. Unless the service is well below standards, some etiquette experts say it is poor taste to go below 15 percent.
"You really have to look at how the people you are tipping are making your life more pleasant and less stressful," said Thomas Farley, a New York-based etiquette expert known as "Mister Manners." "When you examine it that way, it's certainly worth a dollar here or there."
Sometimes the service is so appalling, the server does not deserve a tip, he said. But you don't ever want to just walk out of the restaurant without tipping.
Instead, explain yourself to the server and have a talk with the manager. Mr. Farley does not recommend ever leaving two pennies on the table to make a statement.
"That is a form of revenge," he said. "It is mean spirited and obnoxious. It's also a coward's way out. It takes a lot of courage to talk to a manager about what happened. It's far easier to leave two pennies and run. I expect that type of behavior from teenagers, but not cultured adults."
Federal law allows restaurants to pay servers who receive tips a minimum wage of $2.13 an hour.
They must average $5.12 an hour in tips for every hour they work in order to bring their pay up to the federal minimum wage of $7.25. If a server's pay doesn't average out to minimum wage, the employer is required to make up the difference.
While a tip is optional, a gratuity is not.
A gratuity is sometimes added to the bill when large parties -- generally eight or more people -- are being served. If the restaurant charges a gratuity in the 20 percent range, diners should not feel compelled to leave a tip unless the service was above and beyond the call of duty.
Some pizza stores have begun to charge a delivery fee in respond to drivers getting shortchanged on tips. A $1 tip for pizza delivery was acceptable back in the 1980s, but the cost of living -- especially gas prices -- has gone up since then. The minimum tip now should be $3 or 15 percent if the order is for $20 or more, the experts say.
Paul Brazina, dean of the school of business at La Salle University in Philadelphia, said different parts of the world take different attitudes toward tipping.
In the U.S., he said, tipping is the primary way in which service staff is compensated. In Europe, it is a different story. Servers receive their payment from the restaurants and tips are a modest thank-you for good service.
"It is considered demeaning to leave a big tip in Europe because they are already getting fair compensation," Mr. Brazina said. "They actually look at it as someone who doesn't understand good etiquette. It shows the wait staff you don't consider them professional."
He explained that in western Europe, waiters are career professionals, while restaurant servers in the U.S. are largely working part time for extra money.
Waiters in Switzerland actually buy the customer's meal from the restaurant and sell it to the customer for a profit, which is why they don't expect much of a tip, Mr. Brazina said.
But when it comes to dining out in this country, there is no excuse for not tipping the wait staff.
"I suggest that the only reason not to tip would be the same level of service that would motivate a customer not to pay for the meal," Mr. Brazina said. "When there is rotten food or rotten service, the contract between the provider and the customer has been voided."
There are situations where tipping should be held to a minimum.
For example, the minimum tip of 15 percent should be paid when an employer is reimbursing the meal, the idea being that an employee should not be too generous with the company's money.
But a more generous tip should left for a server if the customer holds a business meeting at the table and stays for a lengthy meal.
"As the server should not be the focus of the meal, the tip should also not be the focal point," Mr. Brazina said. "Good service should be rewarded with a good tip -- 20 percent. Bad service should be reflected with a bad tip -- 10 percent."
Tim Grant: firstname.lastname@example.org or 412-263-1591. First Published May 10, 2013 4:00 AM