@Wes ...
RedHat is somewhat notorious for being 'conservative' with versions it offers from their primary repositories when it comes to PHP and MySQL. Thus adding webtatic, epel, remi repos to the system will provide what is desired.
http://webtatic.com/packages/php54/
Note: php55 is also offered.
You want to follow EL6 info on the above link.
And, would highly recommend editing the webtatic repo file found in /etc/yum.repos.d and set it to in-active to prevent conflicts with other packages ... just interested in PHP and MySQL. To use webtatic repo one will have to add --enablerepo=webtatic to yum commands.
And, strongly suggest upgrading the PHP from 5.3.3 to 5.4 or 5.5 as beginning with Moodle 2.7 there are newer requirements for PHP and MySQL. PHP 5.4/.5 has Zend Opcache built in. Moodle 2.7.x (long term support version) should be the destination (eventually).
Dunno how familiar you are with yum but I've found one has to remove php, php-*, and php-commons from the system first, in order to use the upgraded packages from webtatic. That will break anything running under PHP on server until one installs from webtatic.
While you are at it, may as well upgrade the MySQL version as well. Don't forget to run mysql_upgrade after upgrading version of MySQL ... might have to use a --force option.
man mysql_upgrade has info
'spirit of sharing', Ken