When I was 18 and in high school, I was a waitress at a Pizza Inn for a few months. Back then, regular minimum wage was $3-something and wait staff minimum wage was $2.09/hr. The regular minimum wage today is way too high, but that's another topic.

I always reported my cash tips. Under-reporting is tax evasion, and I don't do that.

I didn't like working there because the place was so slow. One week, the restaurant had to add money to my paycheck because the $2.09+tips was still less than regular minimum wage.

I hate the tipping culture and wish it would go away, but at the moment we're stuck with it. When I go to a restaurant, I usually tip exactly 15%, or zero if the service is poor. I don't do complicated calculations, and I certainly don't consider the employee's personal tax situation.