In Nevada, tipped employees get full minimum wage.
http://www.laborcommissioner.com/faqs.htm
I tip 15% on the pre-tax amount. I hope I don't get flamed, but the restaurant just collects the tax and sends it to the government agency that levies it, and I don't feel my gratuity should be based on an amount that the restaurant and I have nothing to do with. It drives me nuts when I pay with a cc and the server doesn't bring back the itemized receipt (and then I try to remember or even guess what the tip should be); and it also drives me nuts when there's a suggested amount printed on the bottom of a receipt that is based on the full amount of the bill. I ignore that and figure it out myself.
But if it's excellent service, or I make any special requests then I'll tip more.