[jodi]

Hmm...used to happen to me once in a while when I lived in the city, until the store started a policy of giving you $2 when you caught their error. The first week, I caught an error. I had NEVER had one since - and I checked my receipt religiously.
Since I moved back home (rural area), I can only recall a handful of mistakes in years of shopping weekly (and I shop at three different stores regularly). And I still check my receipt ALWAYS before I leave the store - then I can go directly to the Customer Service desk if there is a problem.
(DH is incredibly embarrassed by the fact that I WILL wait in line to recoup a dime - he doesn't understand the phrase "It's the prinicpal"! I tell him that if they are doing it to me, then they are doing it to everyone and someone needs to tell them)