.php Extension On Category Pages?

Hello again good people of the WordPress community! I’m just now getting WordPress all setup and running and i’m trying to get all of my navigation/SEO/etc all squared away before I get too carried away and I just noticed that my category pages don’t have any extensions in their URL’s… Right now, I have my permalinks set to:

/%category%/%postname%.php

I am also running the “.php on PAGES” plugin, as well as the “WP-PageNavi” plugin and the “Platinum SEO Pack” plugin.

Any idea how to get a .php extension on the category pages?

~ Aedryan