In early February a pair of microwave ovens at the south-side Kohl’s store had inch-wide plastic badges attached to their printed price tags. In blocky LCD numerals, they announced the ovens were on sale for $64.99—a big markdown from the $99.99 price on the paper tags. What’s more, for every $50 spent, the store was offering a $10 credit for future purchases. But timing is everything: the very next day, those digital tags read $79.99 and $89.99.

When a customer asked what had happened, an employee said the company sends price changes by satellite, automatically updating the electronic labels. The instant increase was a sharp move on Kohl’s part, since that same day the store ended a week of giving out bonus credits and began a short period for redeeming them. According to the employee, the shoe department also has quick-change digital badges. So far, most other items in the store still carry printed price tags—at more securely marked-down prices.