((You're right, they're not listed. However, in the case of AV rounds and Hi-C rounds, that isn't necessarily an error, since they may be in future books. Just like how Background Count is already named in SR5, it means the info is central in the right place.
As for the others, their costs are missing but can be derived. With Gauss Rifles, they're kinda Assault Cannons so likely their rounds cost the same. For Gyrojet rounds, normal ones are likely Regular in costs, Gyrojet Plus is Explosive so +1/-1, Gyrojet Taser is Stick'n'Shock and Gyrojet Tracker = Tracker, and that determines both their damage and cost. But it's indeed missing in explanation.))