Hi and welcome to the forum, Corey.
The scripts in cpanel/fantastico are sometimes one or two versions behind, so its always best to install it manually with the latest version from the authors site (in this case http://www.oscommerce.com/ ).
This will also give you less problems when it comes to upgrades ofthe script in question.
When you use fantastico installs, the install usually gives the server the ownership of the folders/files and not to you, which you will need if you are wanting to manually change somethingor upgrade it.