I've been known to tip $3 for a $6 bill, and I've been known to tip $.05 on a $15 bill. You earn your tip with me, just like everyone else. You're not entitled to a minimum tip of any percentage, contrary to what some folks think. Good service merits good compensation. OBTW, I'm the kind of customer who is always very polite, quiet, and neat. I even stack the dang plates and put the napkins and stuff in them so they're easier to pick up and carry away. I make it a point to read name tags so I can call the server by name, smile, and say "thank you" with sincerity. But when it's tip time, I do think about how the server behaved, how well we were served, etc. That's when teens who expect big bucks for nothing get a little spare change for a tip...sometimes all in pennies, so they can learn to count.