You must be right - given the figures - but I'm a bit bemused by this GST solution because I think I already have it set up right:

If you ARE registered for GST, you will need to enable this option AND ensure you have the correct TAX rates set for the Australia zone, and again, your customers will be presented with correct GST inclusive quotes.

The fact that you are seeing tax exclusive prices would indicate that you have enabled the GST functions, but haven't set a GST tax amount.
I kept the settings from the previous zencart/ozpost setup before I moved to zencart1.3.9d and ozpost 2.0.8.

I've always been registered for GST so I have it set up like this:



and...



...but my quotes are tax exclusve? Weird.

It's got to be me but has me beat. Sorry to cause you strife.

(BTW - the green admin background is the Green Tea theme - easier on my tired old eyes. Highly recommend if that's your thing too.)