I recently purchased the billing module... is there a way to show tax as 'sales tax' rather than VAT? This is an important feature for US based businesses. I have looked through the manual and can't find any way to change this... any ideas would be much appreciated.
As far as I know, the sales tax is calculated the same way then the VAT in europe. So basically it should be sufficient to rename vat to sales tax in the language files. You can do this with the language editor that is built into ispconfig (System > Language Editor > Languages).