Replace "Ex. Tax" with "Include Vat 23%"

Hello everyone!
Im using opencart 1.5.4 and i cant modify the price format. By default my prices appear like this
Price: 123.00€
Ex Tax: 100.00€

But i want to say
Price: 123.00€
(VAT 23% included)

Additionally for some products the VAT might be 13%.

I was searching all day long but i couldnt find a solution! Please if someone can help me it will be great