Sheridan Nursery Mistake?

Yesterday, I lucked out and was able to find a couple more Bartzella Itoh Peonies plus a Hillary in stock. When they were getting scanned, the total price was way off. So I asked the cashier to please double check as the peonies were on sale. He stated no - only Waterlily and Hillary were. I told him that I was here a few days ago and bought 6 different kinds all on sale. The manager approved the override and I left thinking of the Ikea commercial and yelling to Ryan, "Start the car!".