Point-of-Sale demo code at DNA Lounge.

easyPOS is a GPL cash register written in C using GTK+.

A complete point of sale system including a dedicated back office server, and web based administration interfaces.

The gShop Project is an OpenSource Project to create a fully-featured retail point of sale application, suitable for a range of businesses.

Touchscreen POS for restaurants and food & beverage organizations. Point Of Sale for resale for Linux and BSD.