How do i set the tax to show as a net value in the cart and invoice, at the moment the cart value shows the gross including vat and the amount of vat charged.

Lets assume the product including vat @ 20% has a value of £24.00, what i need to show is as follows

Net Value £20.00

VAT £ 4.00

TOTAL £24.00

Any ideas or help is greatly appreciated.