At one place I patronized recently, I paid cash (several hundred dollars) for an item and was asked for ID and all kinds of stuff - I pointed out to them that US money says "Legal tender for all debts public and private" and asked them "what the hell was the idea?' After an embarrassed pause, the answer was "we don't get much cash for big purchases, sorry." I remarked that I can understand why... much embarrassment later on their part, the owner and almost everyone apologized and threw in a lot of stuff with the item. They really don't look at the money itself, just the denominations. Pay cash and make the shopowners sweat... it's fun and easy.