Upgrading PHP Point of Sale from source code is an easy process. Below descries the process.
When upgrading always make sure you do a backup
Logout of the POS system and REMOVE old php pos folder completely and then upload all code from your point of sale installation with the code downloaded for new release.
Modify PHP POS database configuration file
Browse to "application/config" and look for a file called "database.php.tmpl". Rename this file "database.php" and then open it so you can edit it using your database info.
point your browser to http://yourserver.com/PATH/TO/PHPPOS/
The system will automatically detect it needs to be upgraded. Follow the steps on the screen. NOTE it could take awhile to do upgrade; please do NOT refresh or navigate away from page