Looking at Roman customs doesn't tell us much. If you bother reading (even for example, Daniel, or Maccabees) you find that the Jews tended to get in trouble by resisting the cultural norms of whoever was occupying Israel at the time.
1. Josephus shows that the Jews were known, as Eusebius renders it, for their close-cropped hair (Preparation for the Gospel, IX.9, sect 412b).
2. Leviticus 10:6 —
Moses said to Aaron, and to Eleazar and Ithamar his sons, Do not let your hair be loosely disheveled,
3. Ezek. 44:20 —
Nor shall they shave their heads, nor suffer their locks to grow long. They shall only trim the hair of their heads.