Summing objects property in array

array_reduce could be one way to do it; Just simply add your $array

$sum = array_reduce($array, function($carry, $item)
{
    return $carry + $item->commission;
});

var_dump($sum);

If you are using PHP 5.5

$arr_new = array_sum(array_column($yourarray, 'commission'));

Let's say $arr stores your information. Implement the following function:

function sumProperties(array $arr, $property) {

    $sum = 0;

    foreach($arr as $object) {
        $sum += isset($object->{$property}) ? $object->{$property} : 0;
    }

    return $sum;
}

After that you just have to call sumProperties($array, 'commission').

Furthermore if you have more properties that could be summed, you could replace commission with those properties.