How to count back change: a beginner's guide

Last week I paid for my coffee with a $100 bill and got shorted $10. I doubt the cashier was risking getting fired over $10, so I have to assume she just didn't know how to count change. This morning, a cashier at Arco surprised the crap out of me and counted back my change properly. It doesn't seem to be related to the "classiness" of the shop, or even the age of the cashier -- properly counting back change has somehow become a lost art. I can't begin to know the number of times a cashier has cheerfully dumped change into my hands, or counted the actual bills back into my hand ("there's 5, 10, 12, $12.75. Thanks!"). Maybe it's because so many transactions are cashless these days, but nobody really seems to teach the skill of properly counting back change.

Well, I'm here to rectify that situation. If you deal with cash at all, ever, you should know this easy-to-learn, extremely useful skill. All it takes is knowing how to count cash. Cash registers go down, sometimes you hit the wrong key on the keypad, the customer gave you a $50 and it looked like a $20 so you punched it in wrong, you're selling something in person (not in a store) -- there are a million reasons that everyone should know the proper way to count back change. As an added bonus if you're using a cash register: it doesn't matter what amount of cash you punch in, if you make change this way, your till will always be spot on at the end. I cashiered in high school and college, and every once in a while I'd accidentally key in that the customer gave me $1,000,000 instead of $100, $2,000 instead of $20 and so forth. No biggie -- make change with this technique and it won't matter one bit! You don't even have to void out that transaction.

The concept: the customer should leave with the same amount they gave you. But instead of leaving with all cash, some should be cash and some should be product.

The simple transaction

This assumes your customer hands you all paper money. After your customer hands you the cash, reach into the till and begin counting back to what they gave you, starting with their total. Again, your target is the amount of money they handed you.
Example 1:
Total: $7.75
Customer hands you: $20
Begin counting at 7.75. Count: 8 (quarter), 9 (single), 10 (single), and 10 (ten) is $20. They get .25 + 1 + 1 + 10 = $12.25 as change.
Check your work: $12.25 + $7.75 = $20.

Example 2:
Total: $3.25
Customer hands you: $50
Begin counting at 3.25. Count: 4 (quarter x3), 5 (single), 10 (fiver), 30 (twenty), and 20 (twenty) is $50. They get .75 + 1 + 5 + 20 + 20 = $46.75 as change.
Check your work: $46.75 + $3.25 = $50.

Example 3:
Total: $15.32
Customer hands you: $100
Begin counting at $15.32. Count: 15.35 (penny x3), 15.45 (dime), 15.50 (nickel), 16 (quarter x2), 17, 18, 19, 20 (single x4), 40, 60, 80, and 20 (twenty x4) makes $100. They get .03 + .10 + 0.5 + .50 + 1 + 1 + 1 + 1 + 20 + 20 + 20 + 20 = $84.68.
Check your work: $84.68 + $15.32 = $100. I wrote out all the specific coinage above because you'll do that in your head -- get to $1 as fast as you can. It's ok to hand the customer all the coinage and count to the next dollar.

The complex transaction

Some customers like to get cute with the denominations they hand you. usually there is a reason, like getting back larger bills. For example:
Example 4:
Total: $6
Customer hands you: $11
Begin counting at $6. Count: 5 (fiver) is $11.

In this case they get a single $5 bill back instead of the 4 singles they would have gotten if they had just given you only the $10 bill.

Example 5:
Total: $42
Customer hands you: $47
Begin counting at $42. Count: 5 (fiver) is $47.

Same as example 4.

Example 6:
Total: $12.77
Customer hands you: $20.02
Personally, I subtract the coins they give me from what they owe in my head real fast to see if there's a shortcut. In this case there is: 77 - 02 is 75, so they get a quarter back. Start with the quarter: 13 (quarter), 14, 15 (single x2), and 5 (fiver) is $20.

These examples are the most common situations you'll run into. Practice a little bit and you'll be counting like a pro in no time!