Sry for my english. I will try.
I take a look to: statutory_taxes.html <-- cant put link becouse my karma! :( But, don´t undestand how to do what I want. In argentina, we have a tax really variable, "impuesto no gravado" and is not fixed (not allways the same) and is not %. so is can not setup as porcentual, and off cource, FIXED is not goot too. I want to define a new tax, and I want to set the amount on the fly. (on the invoice) ej:
fuel: 100$ Tax porcentual 21= 21 MY NEW TAX: 30 total: 100+21+30= 151$ how Can I define that kind of tax? is not a porcentual, and is not FIXED, becouse, on the next invoice, is not 30, is might be 39....
Are there any clue? im so sorry for my english, please try to understand :)
Regards,