I dont think 5.0 might understand TLS 1.2 since it is already in its late stages VMware Knowledge Base
However can you provide me the exact version and then we can see how to proceed
VMware products are using OpenSSL
According to this link: https://en.wikipedia.org/wiki/OpenSSL
TLS 1.1 and TLS 1.2 started to be supported from 1.0.0 Released on March 14, 2012
According to this link https://www.vmware.com/support/vsphere5/doc/vsphere-esx-vcenter-server-50-release-notes.html
VMware vCenter Server™ 5.0 | 24 Aug 2011 | Build 456005
See there can't be 5.0 supporting TLS 1.2 as OpenSSL didn't have the support of TLS 1.2 in 2011.
I am leading the team that made vSphere 6.7 to ship out of the box with TLS 1.2 by default.
We have also delivered the TLSReconfigurator tool, so version 6.0 U3 and 6.5 could be configured to be TLS 1.2 only
You know, The End of General Support for vSphere 5.0 and vSphere 5.1 is August 24, 2016.
I encourage you to move to 6.5 U1 version or 6.0 U3 so you could fully benefit from the security TLS 1.2 protocol offers. Both releases have TLS 1.2 support and are great and stable.