The others explained why. The following is the workaround:

for (my $i10=0; $i10<=100; $i10++) {
   my $i = $i10 / 10;
   print "$i, \n";
}
[download]

or the easier to read

for (0..100) {
   my $i = $_ / 10;
   print "$i, \n";
}
[download]

Always use integers for loop counters.

If you need to compare two decimal numbers, check out Comparing Reals using a Tolerance.