With new technology at affordable prices, there is no reason to still double entry information. But this is the case in many businesses. We still have systems not in sync that require busy people to enter the data in two software systems. This is often due to having one good system for the financials like QuickBooks and another piece of software to manage the operational end of things or sales like a POS. They both have a provide a valuable service, but can't they just get along and talk back and forth. Not only is the deficit too high but the software is too stubborn.
There are many great add on software products that integrate with QuickBooks products including the Point of Sale, Field Service Management, Shopping Cart, as well as hundreds of other apps listed on QuickBooks Marketplace website. So stop the double entry streamline your data. It will cut down on hours of mistakes, frustration, and save you money.