#!/usr/bin/perl -slw

use strict;
use warnings;
use List::AllUtils qw/minmax/;

my @points = (
[3.70722,0.54617,],
[3.67342,0.64892,],
[3.75017,0.85075,],
[3.82831,0.83506,],
[3.71852,0.79251,],
[3.80706,0.70426,],
[3.91839,0.94094,],
[3.90726,0.81722,],
[3.89007,0.76107,],
[3.98006,0.62477,],
);


my $bins;
my $binside = 0.1;

my ($xmin,$xmax) = minmax( map { $_->[0] } @points );
my ($ymin,$ymax) = minmax( map { $_->[1] } @points );

for(    my $xbin=$xmin ; $xbin<=$xmax ; $xbin+= $binside) {
    for(my $ybin=$ymin ; $ybin<=$ymax ; $ybin+= $binside) {
        my $p = $points[0];
        if(   $p->[0] >= $xbin && $p->[0] < $xbin + $binside &&
              $p->[1] >= $ybin && $p->[1] < $ybin + $binside ) {
                  $bins->{$xbin.$ybin} = [] 
                  unless($bins->{$xbin.$ybin});
                  push @{ $bins->{$xbin.$ybin} } , (shift @points);
          };
    }
}

print scalar(keys(%$bins));
[download]

#!/usr/bin/perl -slw
use strict;
use List::Util qw[ sum ];
use Data::Dump qw[ pp ];

our $Y //= 10;
our $X //= 10;

my @xs = map -3+rand 6, 1 .. $X;
my @ys = map -3+rand 6, 1 .. $Y;

my %bins;

for my $x ( @xs ) {
    my $xc = ( int( $x * 10 )  + 0.5 ) / 10;
    for my $y ( @ys ) {
        my $yc = ( int( $y * 10 ) + 0.5 ) / 10;
        ++$bins{ "$xc:$yc" };
    }
}

pp \%bins;

printf "Buckets used: %d, total values %d \n",
    scalar keys %bins, sum values %bins;
[download]

You must be using a pre-5.10 version of Perl. Try:

#!/usr/bin/perl -slw
use strict;
use Data::Dump qw[ pp ];

our $Y ||= 10; ## changed from //= for pre-5.10 
our $X ||= 10;

my @xs = map -3+rand 6, 1 .. $X;
my @ys = map -3+rand 6, 1 .. $Y;

my %bins;

for my $x ( @xs ) {
    my $xc = ( int( $x * 10 )  + 0.5 ) / 10;
    for my $y ( @ys ) {
        my $yc = ( int( $y * 10 ) + 0.5 ) / 10;
        ++$bins{ "$xc:$yc" };
    }
}

pp \%bins;

printf "Buckets used: %d, total values %d \n",
    scalar keys %bins, sum values %bins;
[download]

You can vary the number of datapoints generated by using a command line like:

perl -s theScript.pl -X=100 -Y=100
[download]

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

"I'd rather go naked than blow up my ass"

4 is the number of bins. do you need the contents of the bins ? also , the code at the link you indicated is ancient Perl4 code, you don't want to use that.