Little coupon secret

On every coupon there is a bar code that the cashier will scan. Well, those numbers actually mean something. The one that means the most to me is the very first number. If the number starts with a "5" then that coupon will double or triple if the store is offering that promotion. If the number starts with a "9" then it will not double or triple. Many of the coupons I have found on www.coupons.com would print out and say at the top "DO NOT DOUBLE OR TRIPLE". Well, this really stinks for those great promotions that Harris Teeter offers but guess what?! If it starts with a "5" IT WILL!!! I was a little hesitant at first but I tried it last night thinking that I would take whatever it would take off and it actually did triple the value! Now, I'm not trying to get away with something naughty or be fraudulent at all. I gave the cashier the coupon, he scanned it, it tripled, I left happy. It's a win-win!