Brightpearl Electronic Point-of-Sale (EPOS) provides the functionality for dealing with shop-front, customer-facing sales, where you are using a till to hold cash and perhaps taking card payments using a PDQ machine as well. It is an easy to use sales process which allows your employees to work through a few simple steps to complete sales and refunds, whilst also removing access to back-office data. If you have multiple stores you can still use EPOS by setting up separate warehouses.
EPOS works for both Macs and PCs and is online, which means that you don't need to install any software; everything runs in an internet browser. All you need is a receipt printer and (optionally) a barcode scanner and cash drawer.