I spend a few weeks in US every year. There are a few small things that frustrate me.
You never know what a good is going to cost. Sales tax is always added after you buy. This means everything you buy costs something like $4.32. You can never prepare the exact change in advance, so you hand over a bill, and always end up with more change. The interesting thing in the US, is that everyone has jars of pennies lying around the place. People never seem to spend pennies – only accumulate them.
I really loved this video, which showed the economic absurdity of a one penny piece. It articulated what so many people think.
Inflation and function of money