Price without tax + tax = final price

i want to make the price show like like

$50 + $10 (20% VAT) = $60

also show this kind of price at the cart and checkout



i edit the price.tpl and made something like the above but my problem is that the discount amount is also appears like this : $5 + $1 (20%vat) = $6 discount (-10%)



any suggestion please