Adding values from custom fields from a single category

Feel free to laugh but this is driving me crazy. I have spent a lot of time trying to solve what is probably a basic thing in php.

I want the total from a custom field called loan_amount. The code below gives this type of output:

Red Donkey Loan Amount: $300
New Balance: $300
Tractor Loan Amount: $2000
New Balance: $2300

It is returning the correct posts, with the correct values to be considered, and making a running balance. All I want is the final total value, the 2300.

<?php

// The Query
$the_query = new WP_Query( array( 'post_type' => 'post', 'cat' => '4',  'meta_key' => 'loan_amount',  'orderby' => 'date', 'order' => 'ASC') );

// The Loop
while ( $the_query->have_posts() ) : $the_query->the_post();
	echo '<li>';
	the_title();
$custom_fields = get_post_custom();
$my_custom_field = $custom_fields['loan_amount'];
 foreach ( $my_custom_field as $key => $value )
 echo " Loan Amount:  $" . $value . "<br />";
	echo '</li>';

if ($value) {
       $total += $value;
echo "New Balance: $" . $total . "<br/>";
   }
endwhile;

// Reset Post Data
wp_reset_postdata();

?>

Any help would be appreciated.