A Point Of Sale in web interface using CI v 2.X, its a predecesor of the opensourcepos that instead use CI 3: https://github.com/daN4cat/opensourcepos.
PHP Point Of Sale (POS) was designed to small businesses with keeping track of customers, items and inventory, and generate reports based on sales. This program works great for businesses that use cash, check, or account numbers for their sales
simple
The inventory uses SOAP calls, you can define magento or remote SOAP call to that.
please readme the INSTALL.md file, basically, download the code, install mysql, apache2 and setup the database.