Add a % to some currency rates

My base currency is USD. I need to add 2% to EUR and GBP prices to cover my charges.

this doesn't work with 1.5.2.1
http://forum.opencart.com/viewtopic.php?f=20&t=27110

Can anybody point out to me how I can add a percentage to the daily updated currency rates?
I'm willing to pay for this information.

I have a site were i put my rrp in GBP and set the other currency to not update automatic and then type in the rate at wish i wish to convert for example gbp 1.0 mxn 21.00 even though currently its 18 it saves time and stops fluctuation on the site as all goods are bought in GBP and want them to have a GBP RRP but in pesos

the post i linked to has been updated with solution!
viewtopic.php?f=20&t=27110