Thanks for the answers I learned a lot from you on the subject.How often when you go into supermarkets do you see cashiers wearing laser goggles exactly?
Also shops have strict regulations for follow for ensuring safety for their staff and customers. They will not install anything that would present a hazard to yours or anyone else's eyesight. Unless you are facing a severe case of boredom and are staring for periods into the barcode scanners, i can not see a problem here at all.
From what I understand the laser of the barcode is not dangerous to the eyes and the chance that it will damage the retina is small.