Many non-techie business owners are not really 100% sure about the difference between a traditional Cash Register, and a Point of Sale software or system (POS). 

To simplify, a traditional cash register only performs a small subset of what a point of sale system can do.  A typical cash register is just a device where you punch in the amount and at the end, opens up the cash drawer and the cashier gets the payment from the customer and gives back the change.   

Some newer cash registers are programmable where certain keys represents certain products and therefore you just have to punch that key and the value of that product is automatically added.

A Point of Sale System or a point of sale software  performs all of the things a normal cash register does*PLUS* a whole lot of stuff.  Most modern point of sale systems have features such as..

1. Automatically deducts each product sold from your inventory system.

2. Monitors Inventory levels and alert you of products or SKUs below stock critical level which means you need to reorder these items fast.

3. Tracks which items are fast moving items and slow moving items.  This means as a business owner, you know which products sell the most and which ones are not.  You can therefore adjust your stock levels or even discontinue offering a certain product if it just takes up space and does not give you profit.

4. Monitor disposals (if you have perishable goods on stock).  It is best to keep disposals to a minimum.

5. Keep track of inventory so you can minimize pilferage.

6. And a whole lot of stuff.  (see this Infrasoft Point of Sale Software).

So as a business owner, you might want to evaluate the benefits of shifting to a Point of Sale Software System instead of using your old cash register.