Can’t speak for all blind people—but then, really, who can?—but there are a couple of different tricks I employ, depending on time, battery level (that will be made clear in a moment), location and… phase of the moon? It needed a fourth dependency. Anyway…
I keep track of bills by keeping them in a certain order in my wallet. As for determining that order, I can do one of the following:
If the change is less than $5, or the bills are all $1, I just go ahead and trust the cashier. There’s no way they can short-change me at that point.
If I’m out and about, I’ve got software that will read bills… actually built into my mobile phone. It will also read documents on the fly, books, business cards, and the occasional display screen.
If I’m at home or in my office, the same OCR software that I can use to read books, memos, magazines, etc. also has currency recognition, in the event that I lose track of how much currency I have on me.
As for… I don’t entirely remember who was talking about credit card transactions, but those are impossible to permanently defraud the blind individual. Let’s say, just for funzies, that I bought a laptop for $799. Dishonest John runs my card for $1500. I obsessively check my bank records and find the discrepancy. Visa’s Zero Liability kicks in at that point, and I’m not responsible for the extra $701. The transaction receipt would show the one product, so if it really came down to it, there’s your “legal protection” or what have you. This is providing, of course, that I didn’t snap a picture with the aforementioned mobile phone software and verify the receipt myself.
Once again, this is just me, and part of why I have access to all of this is that I could justify it for employment, and my employer has some really deep pockets. Other people have different means, and the question “how do blind people X” I expect has many answers.