I don't see anything different in the V2 rulebook. The Spell Cast Sequence says this:
1) Cast Spell: Announce what you are casting and what the target is. Pay the costs required to cast the spell.
2) Counter Spell: Once the spell has been cast, your opponent has the chance to counter it.
3) Resolve Spell: At this point, the spell takes effect.
Both Jinx and Nullify say that they work during the Counter Spell step. They are both mandatory reveals. Therefore, you are forced to reveal both of them at the same time. You have the choice to pay the mana cost of one or the other, then discard the unused one. (This is the same as having a nullify and a reflect on the same guy)