Calculating tx only on added provision?

[iggycro]

Actually english is not my native language so for that reason I can't even do a search of forum to see if question I got already got answered so if it did sorry for asking it again.

 

I want to open dropship shop and I want to be able to count tax only on my provision. Say something is 10$ which I pay to my provider and I add,for example,2$ and on that 2$ I must add local tax.

 

Inovice should clearly say that cost of product is 10$,provision is 2$ and tax is on that provision 0.50 cents.

 

Is there any solution for this or I need to get custom one?

Thanks!