I keep seeing these security camera pictures of thieves or worse but they are mostly useless. If you want to identify someone then put your cameras at approximate eye level and get a real picture as they come in the door. Today's photos are shot from so far away that the people can not be recognized. A photo of the top of a hat or toboggan will not ID anybody.
In my opinion you should have a camera or two at the entrance. Good quality and not the cheap stuff most businesses are using. A set of cameras at the check out. Have a monitor set up so the crooks know they are being identified. I don't think even a crazy crook would attempt to rob your register while looking at his mug shot behind the counter.
Prevention is the best medicine.
Mike Layne
Chattanooga