Probably quicker to jump in increments of $integer.

$ perl -Mstrict -Mwarnings -E '
my $lower = 100;
my $upper = 200;
my $int   = 15;
my $start = int( $upper / $int ) * $int;
while ( $start >= $lower )
{
    say $start;
    $start -= $int;
}'
195
180
165
150
135
120
105
$
[download]

I hope this is helpful.