I don't understand USAnian coins either, though the soft drinks machine in the Battle Mountain Civic Center will make a disapproving noise if you put the wrong ones in.
I don't understand US notes but that's an entire different story, but I find the coins straightforward: pennies, nickels, dimes, quarters. Fifty cent pieces and dollar coins I don't often see these days. I'm not sure why they call 1c coins 'pennies' and I doubt they are either. They're not very exciting though, we like to make pretty pictures with ours, there's are just, well. Hey, look it's a picture of that damn bird again and it's only a matter of time before Trump legalises the hunting of eagles by rich people. Something has to be more exciting than golf (tbh, everything is more exciting than golf).
Dollar bills, I hate, horrid confusing scraggly things that seem invented so demented Americans can thrust them into other people's grubby paws in their pursuit of tipping for every mundane service. That and negotiating with vending machines. Note goes in, note comes out. Admittedly, US vending machines are better with notes than ours, which simply reject notes because they don't like the weather.