treatment of vat

[Gerard McElroy]

Hi,
    Need assistance on posting of VAT on customer invoices.
        When I fill out customer invoice and post to nominal ledger, the gross amount inclusive of tax
    is posted to acct receivable acct and gross amnt posted to sale account.  I need to split the entries between nett sale and vat (tax). there is no posting entry for vat on sales to nominal accts. 
I thought posting entries did this automatically. How do I achieve this? using v.2.2.9. 
    I think I have correct settings in tax option & tax table editor.

        Regards
        Gerard