Wegman's hasn't been particularly pushing it, and it's not dependent on hardware scanners—it's an app for your phone, that just scans barcodes with the phone camera.
My guess is that it reduces sales. If you can see a total dollar amount accumulating as you shop, you're more likely to stick to your budget, maybe select cheaper items or avoid impulse buys. If you don't know the total until you get to the checkout lane, you are more likely to just pay it rather than start setting some items out.
