CODE:

#!/usr/bin/perl -w
use strict;

# $n is number to round, $d is "divisor" for rounding units
sub roundup {
        my ($n, $d) = @_;
        return ( int( $n / $d ) + ( ( $n % $d ) ? 1 : 0 ) ) * $d;
}

for my $i ( 0,4,5,6,9,10,11,24,25,26) {
        print "$i -> " . roundup($i,5) . "\n";
}

for my $i ( 99,100,101,124,125,126,149,150,151) {
        print "$i -> " . roundup($i,25) . "\n";
}

for my $i ( 999, 1000, 1001, 1249, 1250, 1251, 1499,1500,1501) {
        print "$i -> " . roundup($i,250) . "\n";
}

RESULT:

0 -> 0
4 -> 5
5 -> 5
6 -> 10
9 -> 10
10 -> 10
11 -> 15
24 -> 25
25 -> 25
26 -> 30
99 -> 100
100 -> 100
101 -> 125
124 -> 125
125 -> 125
126 -> 150
149 -> 150
150 -> 150
151 -> 175
999 -> 1000
1000 -> 1000
1001 -> 1250
1249 -> 1250
1250 -> 1250
1251 -> 1500
1499 -> 1500
1500 -> 1500
1501 -> 1750