A new study explores the custom of tipping in the United States. Many Americans give tips to people who perform a job for them, especially workers in the service industry. They pay a little extra to people cutting their hair, driving them across town or serving them a meal at a restaurant. The new survey was done for the website CreditCards.com. Princeton Survey Research Associates questioned over 1,000 individuals. The subjects were asked about how and when they offer tips. The researchers found that men give bigger tips to restaurant workers than women. It also found people allied with the Republican Party give bigger tips than supporters of the Democratic Party. And people who live in the northern U.S. are more generous with tips than those living in the South. The survey found that people who earn $50,000 or more a year give bigger tips than those who earn less than $50,000. One likely reason: the wealthier Americans have more money to spend.