TobyHanna is a real federal credit union in Scranton, PA. A friend of mine that lives there told me the credit union used to call its members “troops”.
It used to be called TobyHanna ArmyDepot Federal Credit Union but had it’s name changed to TobyHanna Federal Credit Union later on.
It doesn't have anything to do with Toby himself. It's possible maybe Toby is a member of the credit union, and received the sign as a member and liked it for its ironic value, so he displays it at work. That part is just speculation, but still a likely reason he keeps it. It's not really made clear otherwise.