Attendant: "Right, that's the RV11 at 490, mate. Gimme a sec 'til I check on the till system to see if we have spare stock."
Customer: "Sure, I'll just wait here and stare at the token big-ass-high-spec-Panasonic-eye-massager here."
Till: RRP £450.
Attendant: "Ah, would you believe it! The price has been reduced by 40 since we put the tickets out...nobody tells us these things, heheh. Guess you can have it at that price rather than £490."
Exactly what I do at work. Customer walks away thinking the trading was forthright, and that gentleman was extremely nice in being so honest. Comes back later on for future purchases.
E.g., in the words of dear Fluttershy:
So make the most of it while you can!