#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11112008
use warnings;

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 $temphash;

for ( @$aref )
  {
  $temphash->{$_->{cname}}{cname} = $_->{cname};
  $temphash->{$_->{cname}}{balance} += $_->{balance};
  $temphash->{$_->{cname}}{total}++;
  }

my $answer = [ values %$temphash ];

use Data::Dump 'dd'; dd $answer;
[download]

Outputs:

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