I work in a another nationwide chain that is rolling these out. They are wirelessly connected to a database so prices can be set automatically and update within minutes. I don't think they want to do individual pricing though and if they did they'd just do it at the register. While electronic tags would make store by store pricing easier, that has already been happening to some extent and it's becoming less common as the industry consolidates.
What these are really for is to cut costs. The store I work at probably used to spend 15+ labor hours a week hanging tags on top of a full time employee just to audit them. The other store I used to work at had two full time employees doing it. There's a special printer, app, tons of different little plastic hangers, and paper to print and hang paper tags. These new electronic tags are shipped in a box as they're needed, are reusable, and are automatically updated.
In an old eco-monkeywrenching pamphlet I read it said they used to leave notes saying they spiked trees even though they had not actually done it. The fact that they could have done it was enough to stall cutting and make the loggers look for spikes.
I'd think if the characters in your story could sabotage a few things on the site they could use that strategy as a multiplier which might also help to avoid people getting hurt.