Calculation Of Tax with Order Total.

I'm processing a Order. Is there a Sum that adds the Tax to the Order Totals.

What I have Done.

Using > FixedRateTaxProvider.

dbo.TaxCategory
Id Name 
1  20% 

The Rate is calculated at 20%.

I'm purchasing a Product. Price of £4.74. Calculated Tax = 79p. All displaying on the OrderSummary Page and on the Invoice but its not adding the Tax to the Order Total when completing the processed order.

. If this by Default.
. Can the Sum be created to add the Tax Value to the OrderTotal.
. If so how.
. Using 2.4

All help higly regarded

Richard