Just received a response from affiliate trail. I haven't tested it yet but I will be confirming asap for others:

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1. Locate the following file: /zencart/tpl_checkout_success_default.php.
2. Find this code in the file: fields['orders_id']; ?>
3. Copy/Paste the following code into the file (just under "fields['orders_id']; ?>")

$affcode = $db->Execute("select * from " . TABLE_ORDERS_TOTAL . " where orders_id = '".(int)$orders->fields['orders_id']."' AND class = 'ot_subtotal'");
$var1 = (number_format($affcode->fields['value'],2));
$var2 = $affcode->fields['orders_id'];
echo ("<img src=\"http://YOURSITE.com/affiliate/scripts/sale.php?TotalCost=$var1&OrderID=$var2\" width=1 height=1>");

NOTE: Do not forget to edit last line in this code - http://YOURSITE.com should be replaced with your URL where you installed Affiliate Trail.
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