I agree with OP, some skills really should be secondarily labeled as "party skills". Bartering should be such one. If a group of people show up at a shop. Why in the world would it not just be the general consensus that the most charismatic of the group haggle for the best deals.
Unless it was a specific intention for a particular person to talk to someone, then that could be that. But if its just shopping, let the guy who talks the best get everyone's bags and do his thing for the group.
