There is something terribly wrong how tax is calculated and displayed in prestashop and invoice.
See attached files
Comments from PrestaShop:
Since the bug contains many issues, I'm going to address them separetely here.
presta sucks: In reply to your "presta sucks" screenshot, please see in file PSCFV-7864-invoice-now-consistent.pdf: inconsistencies in the total in this case have been fixed. You may not agree with the computations, as rounded values are summed, but this is configurable, please see this thread for details: http://www.prestashop.com/forums/topic/350813-16010-testers-needed/
btw: about your "btw.jpg" screenshot, please see the attached PSCFV-7864-invoice-discount.pdf file, I believe it is OK: 49.59 - 8.26 = 41.33 and roundup(41.33*21/100) = 8.68.
3) Admin order confirmation.jpg: this is still broken, see
4) Customer order confirmation: this is still broken, see