UberPOS Non-Product Items

This module allows you to add or subtract an amount in cents to an order by adding a dummy product to the order and setting its price. This way you can add products to an order that don't exist in the web system or give discounts.

It differs from the default open_ring (DP) command in that it does not require a category to be entered for the item. It also allows both adding and subtracting wherease the DP command only allows addition.

This module adds two new commands:

* PLUSxxxx : adds xxxx cents to the current order.
* MINUSxxxx : subtracts xxxx cents from the current order