If there is a check mark in the Izracunaj popust na racunu field in the Purchases &amp; Payables Setup window,  the amount was calculated automatically when you posted the document.
Če je v oknu »Nastavitev nabave in obveznosti« polje Izračunaj popust na računu potrjeno, program izračuna popust samodejno, kadar knjižite dokument.