Here is a potentially scalable approach using an in-memory SQLITE database:

use strict;
use warnings;
use Data::Dumper qw(Dumper);
use DBI;

my $aref = [
   { 'cname' => 'Smart Parking',     'balance' => 10.12, },
   { 'cname' => 'Smart Parking',     'balance' => 10.22, },
   { 'cname' => 'Smart Parking',     'balance' => 10.32, },
   { 'cname' => 'Highview Parking',  'balance' => 20.12, },
   { 'cname' => 'Highview Parking',  'balance' => 20.22, },
   { 'cname' => 'Highview Parking',  'balance' => 20.32, },
   { 'cname' => 'Highview Parking',  'balance' => 20.42, },
   { 'cname' => 'ParkingEye',        'balance' => 30.12, },
   { 'cname' => 'ParkingEye',        'balance' => 30.22, },
   ];
 
my $dbh = DBI->connect("dbi:SQLite:dbname=:memory:");
$dbh->do("CREATE TABLE parking (
   cname    TEXT,
   balance  REAL
)");
 
for my $row (@$aref){
  $dbh->do("INSERT INTO parking (cname,balance)  VALUES ('$row->{cname
+}',$row->{balance})");
}
 
my $sth = $dbh->prepare("SELECT cname, sum(balance) as balance, count(
+*) as count 
               FROM parking GROUP BY cname ORDER BY cname");
$sth->execute;
my $result ;
while (my $r = $sth->fetchrow_hashref()) {
    push @$result, { balance => $r->{balance}, cname => $r->{cname}, t
+otal => $r->{count} }
}

print Dumper $result;
[download]

It produces:

$VAR1 = [
          {
            'balance' => '81.08',
            'total' => 4,
            'cname' => 'Highview Parking'
          },
          {
            'balance' => '60.34',
            'total' => 2,
            'cname' => 'ParkingEye'
          },
          {
            'balance' => '30.66',
            'total' => 3,
            'cname' => 'Smart Parking'
          }
        ];
[download]

Plenty of room for making it more robust and improving performance .. left as an exercise.