In your case IF you want to go with foreach loop than
$sum = 0;
foreach($group as $key => $value) {
$sum += $value;
}
echo $sum;
But if you want to go with direct sum of array than look on below for your solution :
$total = array_sum($group);
for only sum of array looping is time wasting.
http://php.net/manual/en/function.array-sum.php
array_sum — Calculate the sum of values in an array
<?php
$a = array(2, 4, 6, 8);
echo "sum(a) = " . array_sum($a) . "\n";
$b = array("a" => 1.2, "b" => 2.3, "c" => 3.4);
echo "sum(b) = " . array_sum($b) . "\n";
?>
The above example will output:
sum(a) = 20
sum(b) = 6.9