How to load the total amount in Magento

magento_get_total_amount.php

<?php
        // load the latest order
        $order = Mage::getModel('sales/order')->loadByIncrementId(Mage::getSingleton('checkout/session')->getLastRealOrderId());
        // get the total amount
        $amount = number_format($order->getGrandTotal(),2);
        // now you can use the variable $amount in the same page, to print the total amount
        
        // important! please add your own error handling to avoid exceptions or errors displayed on the page
?>

<script type="text/javascript">
        var _agTrack = _agTrack || [];
        // please make sure you set the correct customer code
        _agTrack.push({cid:"XXXXX"})
        // in this example USD is used for the currency code
        // please set your correct currency code or optionally load it dynamically, if you are handling multiple currencies
        _agTrack.push({conv:"USD<?php echo $amount;?>"});
</script>