On Sale or Not?

One of my pet peeves, at least since I've been married and have to buy lots of groceries, is prices ringing up wrong at the register. I carefully select many items when I shop based on their sale price, but I've noticed that when you get up to the register half of the time, the price rings up wrong. This irks me because I feel like it's false advertising. I would not have bought the product had it not been on sale, and had I not been vigilent, I would have had to pay full price. This has happened to me a lot at Winn-Dixie, and it has happened to me several times at Target. Now in a previous post, I blogged about how much I loved Target and the fact that they would change the price for you at the register. Today, not so much. The box of food I put in my buggy because it was on sale rang up wrong at the register. I discussed the wrong price with the girl at the register who argued with me that it was the right price. Finally I told her to just take it off the ticket, but she gave it to me for the sale price. (After she rang me up, I went back and checked and I was right). Anyway, the price difference: $.20! You may think I'm crazy, cheap, or stingy, but it's the principle of the matter. Attention retail stores: Don't advertise your product on sale if it's really not on sale and don't make me believe that I'm getting it on sale if it's not. Please fix your registers if the item is really on sale. And don't make me argue with you at the register. And could you please train your cashiers not to roll their eyes at me. :)
Am I the only one that encounters this?