use strict;
use warnings;

my @nums = qw (0 1 4 5 6 11 14 15 16 20 24 25 26 30 34 35 36);

foreach (@nums)
{
   print "in=$_\t rounded=", round_nearest5($_), "\n";
}

sub round_nearest5  # for an positive integer numeric value
{
   my $in = shift;
 
   my ($last_digit) = $in =~ /(\d)\s*$/;
   
   if ($last_digit <5 and $in >= 10 )
   {
        $in =~ s/(\d)$/0/;
   }
   elsif ($last_digit >=5)
   {
        $in += (10-$last_digit); 
   }
   
   return $in;   
}

__END__
in=0     rounded=0
in=1     rounded=1
in=4     rounded=4
in=5     rounded=10
in=6     rounded=10
in=11    rounded=10
in=14    rounded=10
in=15    rounded=20
in=16    rounded=20
in=20    rounded=20
in=24    rounded=20
in=25    rounded=30
in=26    rounded=30
in=30    rounded=30
in=34    rounded=30
in=35    rounded=40
in=36    rounded=40
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