I have worked retail.... and at one time in a mall that had "state-of-the-art" surveillance. I can tell you that persons most watched are employee's. Most "inventory loss" as it is called.. is lost from backrooms. Cash disappears at the register.
A couple well placed (and easy to spot) cameras in the store will deter the impulsive thief.
Other cameras should be directly over cash exchanges (and counting), back/stock rooms, watching backdoors, trash containers/dumpsters and parking areas. The most comman employee method of thief is to take merchandise out to the dumpster. Then a friend will "rumage" through the trash later... and find the "accidentally" disposed of items.
For a small operation... a locked dumpster, and controlled trash removal... and emergency exit only backdoor, could do more to reduce loss than any camera.
