A Point of Sale (POS) generally covers two functionalities: processing payments (ie either reading a credit card using the appropriate hardware or receiving cash in a till machine) and taking the order (ie being able to track when someone bought something and what along with assorted details and of course to adjust the inventory accordingly).
Megaventory does not integrate with a service which can process payments from credit cards nor can it be connected with a till machine, yet. As such in order to be able to process payments you need separate hardware (usually a standalone credit card reader) and/or a till machine (for cash).
Megaventory however can work as a POS (ie take in sales over the counter) provided payments are processed elsewhere. The typical Goods Out workflow is used for this functionality.
So you can put up a tablet at your store and ask your employees to fill in the products being sold all in a very simple 3-step, fast process. It is also possible to do this through a barcode scanner too.
Of course, it is also possible to print out right away an invoice to hand to the customer along with the products.