Hello,

If you are talking about hot fixes, then yes, they are cumulative. You need to apply only the latest hot fix for the given version. However, upgrades aren't cumulative, you need to upgrade gradually. Here is an example. Lets say, you are on version 5.0 hot fix 3 and you want to upgrade to the latest hot fix and version (5.5R2 hot fix 24). You need to apply the following steps:

Upgrade from 5.0 to 5.5.
Upgrade from 5.5 to 5.5R2.
Apply the hot fix 24 for the 5.5R2 version.

The upgrade packages can be downloaded from here and the hot fixes from here.
I hope this clears things up. If not, please let me know.

Best regards,
Boris Pocatko