Welcome to the CentOS fora. Please see the recommended reading for new users linked in my signature.
The corresponding CentOS version would be 5.6 which is obsolete and unsupported. The current packages for CentOS-5.8 perl-5.8.8-38.el5 can be found on a mirror site near you
. The corresponding CentOS-6.2 version is perl-5.10.1-119.el6_1.1. If you must have the obsolete 5.6 versions then see vault.centos.org/5.6/
If you do not have Oracle support, along with the associated access to repositories and updates, your best option is probably to migrate
to CentOS-5. The section "Migration from RHEL5 to CentOS5" should be generally applicable.
If in doubt about what you have provide more information about your system
by running "./getinfo.sh" and showing us the output file.