I've started to tip for to-go orders, but it's not often that it comes up. Basically, there's one place I like to go that has a schedule that conflicts with my own. On occasion, I'm able to leave work early and catch them at the end of their hours of operation, when they're no longer seating patrons, and the only option is take-out. Either that or I've clocked out for an extended dinner break, and I get that to-go as well, since I'm usually taking food back for a coworker. In any case, they're very thoughtful in how they prepare the food for transportation, and to me, that's just as valuable as refilling my water and checking up on me.