Hmm I would precise that, even if you only sell to private customers, you have to show your shop VAT number in the invoice, so it's equally important that the Tax price display issue.

I agree that the tax should be calculated per item basis, or we will have rounding issue on the checkout page (as I have on my shop). The problem is that we have to store the price excluding tax somewhere because this is the base of all discount calculation.

The major problem with tax is that the tax have to be calculated at the very end in the invoice (and checkout page) but, at the same time, each product must be showed including tax.

And the way ubercart calculate the subtotal ATM make this not possible.