Instead of giving me a tab with a blank for a tip, the waitress asked me if I would like to add a tip. If I said yes, I had to tell her how much, so she could go prepare the slip for me to sign. Let me say, I don't like this. Not at all.
Now, I'm a pretty good tipper, but I guess there are many who aren't. I suppose they get more in tips by doing this, but I find it embarrassing. But I don't want the waitress to suffer, so I tipped in my usual manner.
My slip came back to sign, and I was shocked. Instead of merely adding my tip to the cost of the meal (including tax), my tip had been added to the cost, then sales tax assessed to the whole. In other words, they assessed sales tax on my tip. I'm not sure this is legal. I know for a fact it's not ethical.
The upshot is, when I'm using a card, I will never tip at that restaurant again.