We're due for some upgrades, but here's what we're currently running:
IC: 8.1D (120512)
OE: 8.1E (120907)
I believe these are the only ones needed to figure this out? Ideally this info would also flow to our POS system, but I haven't been able to test, as it's not setup within Inventory properly yet.
Not sure about what you'd need to know for the tax groups - here is a screen shot of the Item Rates portion:
