So today, it was my third ever cashier shift, and a guest came to my lane with a full cart, mostly with clothes and large boxes. She had so much stuff that eventually I had to start moving bags directly to her cart because my counter was full and she made no effort to transfer them, instead opting to scrutinize the register screen to constantly verify what she had, what it cost, any sales, and asking me which line on the screen corresponded to what product was in her cart. After ringing up nearly $300 worth of items, she demanded to know why several items she'd gotten off the 30% off rack weren't ringing up as such. Cue internal groan, because I knew almost every time someone mentioned the 30% rack, it was with the Cartwheel discount that the guest has invariably never heard of. The woman downloaded the app, and I asked another cashier who was familiar with it to give her a quick rundown. After about 10 minutes, she showed me the barcode to scan, and I scanned it. Then she muttered about finding the next item for a discount. I knew at that moment that this was gonna be a PITA because I'd already scanned her phone once. I was giving her the benefit of the doubt because she was older and the technology was legitimately confusing her. I asked the other cashier if you could scan Cartwheel more than once, and she said she didn't think so. I flipped on my light and told the GSTL the situation. The GSTL fiddled with the register only to confirm that you can only use Cartwheel once, and it cannot be line voided. Either the guest can take the discount she already has, or the entire transaction has to be voided and started over. I'm sure you can guess what she chose to do. The GSTL gave me an apologetic smile and said, "sorry, you gotta do it all again." So while the guest continues to fiddle on her Cartwheel App, I'm busy unloading an entire cart with stuff inside and on the bottom back onto the belt and unbagging every item. She's completely oblivious to what I'm doing, instead shoveling through the things on the belt to check EVERYTHING. I then rescan and rebag everything again. I had to fight the urge to throttle the guest when at the end of this entire ordeal—which took a little over half an hour to resolve—it turns out she saved herself about $5…off a 270-something dollar purchase. At least she apologized. I guess it was an honest mistake.