OK, so not entirely about tipping, but it really confused me when I visited the USA and read prices for things, then when I went to pay they added tax on after that. And then often a tip. So when I read the price I was supposed to do a bunch of maths to work out if I would actually be able to afford the item once everything had been added. So confusing and annoying.
That and they expected me to pay to the cent (they call them pennies. Go figure...) rather than the highly superior system I'm used to of rounding up. So $2.38 had to be paid exactly. Eeeesh, so very confusing.
On the subject of tipping, whether they were trying to increase my tip or not, I had some of the best service in the US that I've ever had. Fantastic waiters and waitresses.