They will not round "up" or "down". Instead they will round "out". Rounding out the space in the nine 9 into a full-on 0 for 3.300! 😛
I would imagine that if it is out to two places then the 3.399 would become 3.40. If out to three then the 3.399 will hold. But I really don't think the discrepancy will push a decision either way. At least I hope not. Hopefully someone out there knows the answer with certainty, but I believe the general rounding procedures will hold.