Dollar-stores overcharge customers while promising low prices

This very rarely happens in MA, because when it does the store has to give you the item for $10 off, including if that makes it free. And they have to post a sign at the register explaining the law, which means when you're invoking it all you need to do is point at the sign.

https://www.mass.gov/info-details/consumer-pricing-accuracy-...

Where I live there’s no such rule I can tell you no one is correcting the price when I point out that I got overcharged (they usually shrug with “it does that sometimes”).