Creating an invoice without GST for each item but automatically adding GST to the total.

Hi sf17 , your question could possibly be resolved by using two invoice forms, one priced inclusive of GST and one showing prices excluding GST, with a GST total at the end. 

The way you prepare invoices will be the same for each type of customer, unless you wish to modify the "GST-inclusive" flag for each invoice. 

The way your items are priced is set within the item definition, where there is an option to treat selling prices as inclusive or exclusive. 

All these settings are independent of one another.