Most people grab the receipt, or decline it entirely, without a second glance. But checkout errors do happen. A sale price might not ring up correctly, an item might be scanned twice, or a coupon you meant to use might not apply.

Watch the screen as items are scanned when you can, especially for sale items. Before leaving the store, take a minute to look over the receipt. If something is wrong, customer service can usually fix it on the spot, and some stores have policies that favor the shopper when a price scans incorrectly.

Receipts are also a useful tool for spotting patterns. Saving them for a few weeks, or checking digital receipts in your store account, can show you which items you buy most often and how their prices change. That makes it easier to recognize a genuine sale and to stock up when your regular staples drop in price.