You might be concerned about your customers being able to see the amount of the order in the browser's location field once they reach the Thank You page. This can be perceived as a privacy issue (though assuming your transactions are SSL-encrypted, it should not really be an issue, and if they are not, passing the amount in the URL is the least of your concerns). To avoid even the appearance of a privacy hole, you can include one additional redirection page between the authentication script and the Thank You page. The order total parameter is passed to this redirection script, so the transaction is recorded in the log, and then the visitor is instantly sent to the Thank You page without the order total parameter. Your customer will never know the amount of the sale was passed—and neither will any one else.
An alternative method is to call a specific image from your server and pass the order total as a parameter on the call to the image:
http://www.yourdomain.com/images/ct_ecommerce.gif?ct_ecommerce=9.99
where 9.99 is the amount of the sale. This method is described in more detail in Ecommerce with Logfiles and a Third-Party Ecommerce System. It is mentioned here because it could be used as a less visible way of recording the order total.
With the ClickTracks Hosted or JDC method, you can obscure the recording of the revenue amount by including it in the JavaScript code, as described in Ecommerce with Logfiles and a Third-Party Ecommerce System. The visitor will not be aware that you are passing the sale amount, because it will be included within the code of the site with the generic parameter named "e."
<script src="http://stats.clicktracks.com/cgi-bin/ctasp-server.cgi?i=abc123&e=9.99">
</script>
