How can I remove the php file extentions from ecart?

Greetings WebAssist team!

I have a question related to the functionality of the checkout pages. I recently updated my servers .htaccess file to ignore all php file extensions for a cleaner look, for better SEO, and to hide the programming language underlying my websites. All went well with this project except when it comes to the checkout pages. For some reason, when you get to www.mywebsite/checkout, the confirm_cart.php file does not get loaded after one enters the customer address information. I "fixed" the issue by having all references to the checkout pages to include the php extension, as in www.mywebsite/checkout.php. Any suggestions as to how to get this to work will be greatly appreciated as usual. : )

Thank you,
Robert Crespo