must you then collect (and, eventually distribute to the gov't) National Sales Tax (NST) from the entity that buys your shares?
I wouldn't think so.
How 'bout that used car?
Again, I wouldn't think so - tax was already paid on it. You'll be paying sales tax on the fuel, oil, and parts for said car.
Or Software consulting services?
Harder question, but it its true services, no different than what's now.
Or barter?
Nope. Just like now. But you'll have paid the tax on whatever you bought to barter with, or the raw materials (in most cases).
The other cases are going to be limited enough that I don't think right now its a concern.
Addison