5 and 10 are arbitrary numbers though. Halving and doubling are really the only special operations, and base-8 or base-16 would be superior to 10 or 12 for those.
You can use hexadecimal numbers if you wish. "He's B6 cm tall."
I have found this, which seems neat: https://en.wikipedia.org/wiki/Bibi-binary
So he's ki-ba cm tall.