The minimum amount to tip a waitperson is 15 percent of the total bill before tax, 20 percent for good service or higher for impeccable service, reports BusinessInsider.com. Even for bad service, it is inadvisable to tip below 15 percent.
CNN.com advises tipping 10 percent for bad service, but BusinessInsider.com suggests tipping anyway and speaking to the manager instead about less than stellar service.
Tim Urban, a New York City-based blogger who writes for WaitbutWhy.com, polled 100 New York City service workers about tipping norms. His findings show that 17 to 20 percent is the average amount that patrons tip a waitperson, and high tippers give 20 percent or more.