I don't think any HALO is done using round canopys.
Your correct. Their a special bread of military jumper. AFAIK only jump in Small groups etc etc and the seal may even jump rounds depending on the mission.
Even saw a smole jumper in alaska on the telly the other day on "Flying wild in alaska" jumping sqs.
The paratroopers on a mass jump, IMO They need to jump rounds to prevnt them from runing into ea other.
Some experienced Sport jumpers still haven't figured out how to keep from running into ea other under canopy and they have a lot more experience than Airborn.
Smoke jumpers jump both round and ram air. It depends on if they are with BLM or the feds. seals jump ram air. Maybe someone at TacAir can chime in on if they ever don rounds.