use strict;
use warnings;
use POSIX qw(ceil);
use POSIX qw(floor);

my $num = 11;
   $num =~ m/\d*(\d{1})/;

my $check = $1;

if($check < 5) {

  $num = ceil($num/5)*5;
  
}else {

  $num = floor($num/5)*5;
}

print "\n $num \n\n";