No, your statement is incorrect.
Please read:
http://www.ato.gov.au/taxprofessionals/ ... 5&st=&cy=0
We take the line item approach because otherwise GST becomes inconsistently calculated when reporting by product group sales, etc.
I.e., you have product group (A) and product group (B) = total sales.
If you run a report for product group (A) and a report for product group (B) and then add the GST together, you will end up with a different result than had you run the report for total sales.
The line item approach avoids these types of problems.
Also, GST calculations have not changed in CAPITAL since the '80's or possibly early 90's at the latest.