CentOS 7.0 and later include a shared store for certificate authorities.
You can find out more information about this shared store by reading the
following manual page on a CentOS 7.x system:

 $ man update-ca-trust

In previous versions of CentOS modifying the distributed certificate bundles
(such as /etc/pki/tls/certs/ca-bundle.trust.crt) was the defacto way of adding
an additional trusted certificate authority to the system.

These additional trusted certificate authorities must be ported forward to
the CentOS 7.0 system manually. You can place them as certificate (PEM or DER)
files in the following directory:

 /etc/pki/ca-trust/source/anchors

And then run the following command

 # update-ca-trust

Please read the update-ca-trust manual page for more information.