My son was able to learn about a fun little law that Michigan implemented a long time ago to fight negligence on the side of retail businesses. The Michigan Bar Code law was put into place to keep businesses from advertising one set of prices and charging another at the register. The problem was so bad that the legislature stepped in and created that cool little law stating if a consumer found the problem and came back into the store with it, they got their refund plus 10 times the amount mischarged up to a certain dollar amount.
He was overcharged by 40 cents for a little notebook and was very happy to walk out with an extra $4.00.