Hiya
Firstly, you'll need to calculate the Net and VAT amounts for each rate using e.g. Excel.
Then, assuming you are entering the transaction through program 4.2.1 (or Cash Book > Enter/Change Journals > Enter/Change Cash Receipts/Sales) when you get to the field just to the left of VAT Amt, put a M in there (for multiple), then put the total amount of VAT in the field next to it.
If you then press Tab, a new form should appear in which you can do a rate-by-rate breakdown.
Hope this helps!
Douglas.