Well, in Brazil 10 percent is already included in the check, it's "optional" but everybody accepts it. Usually that's not related to good or bad service, it's the common practice. And this money doesn't go to the server but to the 'proprietor'.
That's especially interesting to me, as it's generally considered bad form in the US to tip the proprietor, and even worse form for the proprietor to accept the tip if offered.
