@waruwaru,
If you run the cert test using lower version of ESXi 5, you will automatically be granted for the certification for the higher versions of ESXi 5.x.
In my case, I run the cert test on ESXi 5.0 U1, so my products are automatically certified fy 5.0U1, 5.0U2 and 5.1. However, it is not certified for ESX 5.0 GA.
Therefore, in order to save certification test effort, I would suggest you to run the cert test using the lowest 5.x version that you need your products to support.
Hope this helps!
Regards,
Wen