Shipping method - How to add a persentage to insurance

Hi there,

I am working on a cs cart website and I am stuck with the shipping method / insurance section.

I have 4 shipping methods, 3 of them works fine. However the last shipping methode I have, has a standard price per kg and I must include/add 2% of the price into the shipping fee for insurance purposes. Can this be done? My shipping fees are chargerd according weight dependencies.

Not sure if the screen shot is useful. I am working in ZAR (R) currency.