Re: I do wonder...
"Like who told cashiers to put the coins ON TOP OF THE DOLLAR BILLS and then hand the pile to you."
Please sir, please sir, I know that one!
When cash registers only added up the sales total, the sales assistant had to work out the change from the money tendered so did a backwards subtraction, ie adding to the sales total until they reached the cash tendered total so started with the smaller values, the coins and ended with the notes(s).
Modern cash registers total up the goods value then the assistant enters the amount of cash tendered and the cash register tells them how much change to give. Given that value, the sale assistant now starts with the highest denomination and works down to the smallest until the total change value is reached.
Yet another chore of daily life we can blame on computers :-)