I was taught that 20% of the final bill is a tip for a good waiter. I would tip lower depending on the service. I remember going to a restaurant with my mom's side of my family for x-mas. It was a steakhouse, and they added gratuity into the sales ticket at the end of the dinner not giving you a choice on how much to tip them. I took my girlfriend and ended up having to pay her bill which I got separate, but they added gratuity onto that ticket as well. I had like a $70 ticket for a single persons dinner. It was ridiculous.