Geozone shipping method adding 20%

Hi guys,
I have created the geozone shipping method for
Fot light items and woking fine.
Canada $3.00
Us $5.00
all ther country $8.00

Now i need to add 20% on top of this configuration for heavy items like this.
Canada $3.00 + 20%
Us $5.00 + 20%
all ther country $8.00 + 20%
Anyways of doing this?

My Product-Based Fee module sounds like it would work for you. You could set up a 20% flat rate fee and then select all the heavy items. That way it would add the fee separately from the shipping, but shipping would still be standard for all items.