As a former server, I understand that the person taking the order is responsible for not only packaging the order, but also making sure there are condiments, utensils, ect that go with the entire order. When I was a server, we made $2.13 an hour and had to claim the togo sales as regular sales at a table, so, yes, I would recommend tipping the to go person. I would say that most servers/former servers would agree that 10% is appropriate, as we are not clearing dishes or refilling drinks, but, it still takes away from TIPPING tables to gather an order for a TOGO.
On a side note, if you frequently order to go from a restaurant and do not tip, trust me, the people responsible for gathering those orders remember your name after a while...and I for one would not want to be on the receiving end of an order of someone that I knew I was deliberately stiffing a tip for service on.