I am not sure exactly what you're looking for, or how much retail environments differ from food service, but bad or flakey power has caused us the most head aches over the years... bar none. In the food service industry, we're surrounded by large compressors that like to kick on and off and wreak havoc on the circuits. Blown computers/touch screens, strange anamolies, intermittent problems, you name it... We put power conditioners at every station, no if's, ands, or buts... they accomodate the monitor, printer, and workstation. They are small, but effective. Then a big UPS on the back office.
Ever since we demanded this be attached to devices we sell (minus the Epson kitchen printers... probably not a bad idea to protect those too, but we don't see problems with them), our failure rate of new equipment and strange problems has dimished significantly. Don't be fooled into thinking a "dedicated circuit" (i.e. organge outlet) is enough. I've seen problems with these too, whether it was a botched job or they aren't as effective as people think, I don't know. Find a good brand, like SmartPower, and stick with it.