Fuel Levy

With the current high price of diesel many companies are adding a fuel levy to their invoices. It is generally charged as a percentage of the total invoice. We wish to do the same. However, it does not seem possible to do so with any ease in MYOB. I have been instructed by a MYOB consultant on the phone that the only way I can do this is by adding an item, Fuel Levy, entering its cost as $0 then, on each invoice, manually adding the 10% (or whatever) levy. It seems farcical that MYOB considers this an acceptable solution. It is supposed to be Accounting software and to not have the ability to do this basic calculation is laughable. Of course, MYOB was very easily able to manage to add a 16.7% increase to our monthly fee from April 1. And not a drop of diesel involved in desktop accounting!