How to Create taxes that are not a percentage of Total price

[selectum]

Hi all,

I need to find a way to set taxes that are not related to the final price but could be related to attributes of the product such as Size. Is there any way to do this?  

 

For example:

 

that tax is paid by ml , lets say you pay $0.01  per ml

 

then a product of  300ml  would pay $3 tax

and a product of  500ml  would pay $5 tax

 it doesnt matter the price of the article,

 

 

Thank You