I'm from the land down under

I'm just wondering how I can go about implementing our GST Tax into it.
Its 10% on everything.
The shop is only going to be AUS wide so
http://www.opencart.com/contribution/ca ... egory_id/6
http://www.opencart.com/contribution/in ... tion_id/31
I don't think is what I'm after, although I'll take a look at them tomorrow as I'm very tired now

Hopefully ill have some feedback when I wake up, if not ill bust my brain to work it out
Thanks in advance.
pdes