It's always bothered me that there's not a single word for multiples of ten and a single word for multiples of five. It bothers me because society determined long ago that these "round" numbers were far more important than others (e.g. the 75th anniversary gets far more attention than the 74th). To that end, I'm creating two new words.
decager: any integer containing a zero in the ones column; examples are 0, 10, -20, 250, 370
quinteger: any integer containing a zero or a five in the ones column; examples are 0, 15, -80, 250, 375