Clever Discounting

I went into a jewelry store today that had big signs out front reading, "Up to 70% off!" Inside, most of the displays were labeled with "Everything here 50%, plus an additional 20%!" At first blush, that's 70%, right?

Wrong. Since the 20% is taken off after the 50% off has been calculated, the 20% only applies to half the retail price. That is, 10% of retail, which makes the item actually 60% off, a perfectly valid amount in "Up to 70%."

60% off was a perfectly good discount for the item I purchased, and while I'd prefer 70% off, that 10% was in some ways worth observing the cleverness of the discounting scheme. Caveat emptor!