### BEGIN OF tie_rounded_hash MODULE
require 5.005;
use strict; 
#use warnings;
#use diagnostics -verbose; 
    
    
package tie_rounded_hash;

BEGIN {
    use Carp;
    use Exporter ();
    our (@ISA, @EXPORT_OK, @EXPORT);
    our $VERSION = '1.0';
    @ISA = qw(Exporter);
    @EXPORT = qw();
    @EXPORT_OK = qw();
}
our %Rounded = ();
our %List = ();
our @EXPORT_OK;

#sub TIEHASH  { bless \%List, $_[0] }
#sub FETCH    { $_[0]->{$_[1]} }
sub STORE    { $List{$_[1]} = $_[2] }
sub FIRSTKEY { my $a = scalar keys %List; each %List }
sub NEXTKEY  { each %List }
sub EXISTS   { exists $List{$_[1]} }
sub DELETE   { delete $List{$_[1]} }
sub CLEAR    { %List = () }

sub TIEHASH {
    my $self = shift;
    my $rounded = shift || 0;
# rounded is the number of digits to leave to the right of the decimal point.
    croak "usage: $self <#of_digits>" if @_;
    bless {Rounded => $rounded, LIST => \%List}, $self;
}

sub FETCH {
    my $self = shift;
    my $key = shift;
    if ($self->{Rounded}) {
        return sprintf("%1.*f",$self->{Rounded},$List{$key});
    } else {
        return $List{$key};
    }
}


1;
### END of module

### example script
use strict;
use lib qw(.);
use tie_rounded_hash;
my %test;
my %rounded;
tie %test, 'tie_rounded_hash',0;
tie %rounded,'tie_rounded_hash',2;

for (1..100) { $test{$_} = $^T/$_; }
for (1..100) { print "$_ => $test{$_}\t $rounded{$_}\n"; }