Grocery Shopping

Why hasn’t someone thought of this yet…

Wouldn’t it be awesome if you could goto the grocery store or Target or something, and as you put items in your cart, a little LCD screen attached to the cart would tell you how much you have in the cart as far as price goes? Maybe they need RFID on all items and a reader in the cart. I just hate getting to the checkout and then finding out how much it all costs, I why should I have to calculate it in my head as I shop..its 2005!