He’s European and uses a “.” instead of a “,”

Varies by country in Europe.

Varies by country on earth [citation needed].

You’re also not correct even if it were a decimal marker. Three dollars and fifty cents requires no half cent.

Specifying the second 0 implies portions of one cent. Like if I said something costs 10USD, the one dollar bill is implied to exist even if it isn't used (same with 10.00 implying the existence of a penny)