I have been chased down a couple of times in the past few years in Shanghai for having tipped! I spent up to my very last cent when I visited NY in 2008. I could only tip $1 the last evening at the Iridium (Steve Kuhn/Eddie Gomez Trio) when entry fee +drink were around $35. I apologized when the waiter double-checked his tip, but I found his insistent complaint quite rude. I had a breakfast for two in North California the year after. $14. I gave a 20 dollars bill asking for 3 dollars in return. "Something wrong with your breakfast, Sir?" is all I could get in return, repeatedly, at first. Now I always tip separetely and I try to keep as much change as I could. Not much tippers in France, service is automatically included. I usually tip from 1 to 5 euros, but mostly based on the quality of the service rather than on the price of the bill.