I created a general Point of Sale (POS) software in VB6 which was designed for Video Rental stores however it is currently used in production in Restaurants similar to your example.

In my POS application I allowed unlimited levels (theoretically) of ListView items which were configurable through XML files. The XML files were loaded into Collections of objects that drew the screen and performed the calculation appropriately depending on how the configuration was setup. A slightly different twist on the configuration is to make it RMDB based which allows more efficient queries which will then allow real-time updates from a "Management" application or instance. Just a thought. I just figure that if you are having difficulty with one solution find a simple and fast alternative path to get where you need to go. I would be willing to review source if you are interested in my help.