Generally speaking all prices listed are GST inclusive at least for consumers and store fronts. You pay what the price sticker says.
Where it breaks down for us is that GST revenue is split on a determined percentage per state that is unrelated to where it’s collected. There is some sense to that but it also causes problems as there is a strong imbalance which is argued about.
On a related note we do have a 5% payroll tax on all salaries in businesses paying over some figure I think $2m/year. This apparently goes to the relevant state and is one of our little inconsistencies left compared to what is on the whole quite a good federally administered system by one agency. One tax return. One tax rate.
Not to mention that competition lowers taxes for sure.