They are impossible to force open or carry off. Robbery Protection, The decal and the safe statement usually discourages would be robbers. Video Surveillance Camera System, either real or dummy is quite a deterrent. Don't keep visible large amounts of cash in cash register drawers. Drop all large bills on the hour.
Cash is an invitation to robbers.
The patrol car will follow you and wait until the deposit is completed. They will most likely need thirty minutes advance notice in case they are on a complaint. The other plan that I personally use is a two vehicle money drop. Much more security especially with a cell phone. They often tear and the contents spill out into the safe.