[daveFNbuck]

If it rings up for $12 when it's labeled as $10, you can usually get it for $10 if you tell someone it rang up wrong.

[smeyer]

In MA it's even better: if a grocery store item was labeled as $10 and rang up as $12, you'd just pay $2. The rule is that the item is free if it's less than $10 and $10 off if it's more than $10 (although this only applies to one item; you can't just go grab 20 of them).