The rules of tipping in restaurants vary among nations and culture. In the United States, 15 percent is considered customary for average service.

However, a new '60 Minutes'/Vanity Fair Poll 990 American adults has found that a good chunk of diners typically give more or less than that percentage.

According to the survey, eight percent usually tip over 20 percent, while 33 percent tip about 20 percent.

Thirty-three percent also tip the standard 15, with eight percent typically putting down about 10 percent and three percent usually leaving less than 10 percent. One percent of the survey's respondents said they did not tip at all.

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