Changing # of woocommerce columns on category pages

Hi there! I have been trying to no avail to get the products into columns of 4 or 5 on the archive pages. Used a plugin, didn't work. Added stuff to the functions.php, didn't work. But I thought, I bet the WPMU dev people can solve this!

Here is the page that is showing 3 columns:

http://69.175.76.186/~johnhowardcompan/product-category/plastic-buckles-hardware/center-push-and-cam-buckles/

Thanks!