I get the concept of shifting the entire tax burden to sales taxes, but I think it would put the brakes on shopping and create a "Black Market", especially for big-ticket items. I think many people would refuse to buy new and choose used (already taxed) items.
I came up with the "worldwide gross" idea as a way of making foriegn companies pay for the damage they do to our economy by adding a layer of taxes to their cheap-ass products. They COULD choose not to sell here and that would be fine with me!