Well, after checking out with 5 boxes of Post Cereal @ the $1.57 price, a $5 coupon will print up for your next check out. Then buy another 5 boxes @ the $1.57 price, and scan that $5 off coupon for the next check out. This will take the price of the cereal down to 65 cents a box! Each check out (as long as you check out with 5 boxes of the POST cereal), a new $5 off coupon will print up for you.
Trying to eliminate any annoyance, I just did the self-check out. Just remember, that most debit/credit cards will limit the number of transactions you can do in a single day (Cumorah Credit Union is 10 per day), so don't go too crazy!