specials - show price with tax in admin, how do i do it?

In Australia the displayed/advertised price must include sales tax.

The specials admin page displays the net (pre tax) price only. This is a bit of pain to calculate a rounded special price. i.e. discount a product so the final retail price inc sales tax is $129.00 It takes extra time to do the calculations right so I don't end up with $129.12 or some other odd amount.

What I want to do is have the gross (inc tax) price displayed so I can enter in the sale price including tax.

Or the next best thing would be the final price being calculated and displayed when I enter the discount in (like in the add/edit products)

Is there some way of doing this?