I finally managed to find someone who knoew what they were talking about.  You need to go to Settings, Markets, Australia, Duties and Import Taxes, under Storefront and Checkout Pricing, change the option to Dynamic (Include Taxes in Product Price), ...

We need GST included in our product prices.  I have read all the forums that show the tick box to include GST in the price, however it still keeps adding GST after the fact in checkout.  Is there any other setting I need to select to make this work? ...