#!/usr/bin/perl
use strict;
use warnings;

my $begin = 5;
my $end = 7;
my $step = 0.1;

for (my $i = $begin ; $i <= $end; $i += $step ) {
    print $i, "\n";
}

__END__

# -- OUTPUT -- \

5
5.1
5.2
5.3
5.4
5.5
5.6
5.7
5.8
5.9
6
6.1
6.2
6.3
6.4
6.49999999999999
6.59999999999999
6.69999999999999
6.79999999999999
6.89999999999999
6.99999999999999


#-------------
# Setting $begin = 6
#-------------
6
6.1
6.2
6.3
6.4
6.5
6.6
6.7
6.8
6.9
7

#----------------
I get this imprecise addition effect to different extents for different values of $begin.

$> perl -v

This is perl, v5.8.2 built for i686-linux