Figuring out how much to tip at a restaurant in the US can be a tricky endeavour, fraught with a good share of mathematics and emotions. Here are some tipping tips.
In the States, 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 US 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 behaviour," said April Masini, an etiquette expert based in Florida, 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."
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.
Servers at a sit-down restaurant who wait on diners hand and foot expect to receive a tip ranging from 15 per cent to 20 per cent 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 per cent.
"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. 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."
US federal law allows restaurants to pay servers who receive tips a minimum wage of NZ$2.60 an hour.
They must average $6.27 an hour in tips for every hour they work in order to bring their pay up to the federal minimum wage of $8.88.
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 per cent 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 petrol prices - has gone up since then. The minimum tip now should be $4 or 15 per cent if the order is for $25 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 US, 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.