Le magasin de Serge

4 modes are available:

* Pay freely
* Pay the account right
* Give back change
* Whiteboard, for handling currency.

Different options are adjustable:
* Enable/disable decimal numbers.
* Enable/disable 2 items.
* Set the maximum price of items.
* Enable/disable available cash by clicking on it.

On the main page, click on the "info" button to find out how the different modes work.