In regards to Biblical citations, you don't provide me with a print copy of what you are referring to so I can only go by what you stated. IF the book you are transcribing is NOT primarily devoted to religious topics, I would follow print. 17.5b (5th edition) states: In standard prose, references to the Bible, Koran, and other religious works should be brailled as they appear in print. There is not an example showing Roman Numerals, however, I believe the "follow print" rule covers you here.
Hope this helps.