A point of sale inventory management system is a step up from the use of a cash register. Small, start-up businesses who sell services and not products may be able to survive with just a cash register and a simple accounting system. If your business is product-based, chances are you will eventually have to switch to at least a basic point of the sale inventory system.
With a point of sale system, you don't have to worry how much inventory you have on hand. The point of sale system keeps track of that and you have the information at a glance.