To be honest it all depends on what you order. Some meals can be put it one bag in two minutes but if you order something like fajitas for two then its going to require a bit more effort and time consumption to get it all packed appropriately. When I did to-go’s I never expected to get tipped the same as a waiter since I was dealing with customers at ten minute increments. A $1.00 per takeout order was pretty much average, $2.00 - $3.00 from the regular after work commuters and anything above that was a surprise.

Since I was a cocktail waitress in college, I ALWAYS tip a minimum 20%... if the service STINKS however, I will drop it to 10-15%.

Sure, I had a few cheapskates, but I easily made enough for rent
and partying working 3 happy hours a week and one full night.
If you are good at what you do and work in a trendy establishment, tips should never be a problem. Women were the worst, because a few would remove some of the tip their husbands/dates left. (An exception was this AWFUL guy I once dated.)
Since I've been on both sides, I can read a situation better than those who have never been in the service field. I KNOW when it is the wait person's fault or when the fault lies in the kitchen.

Home delivery-15%.

I too carry my own bags and Hubby parks the car.

I usually leave about 20% tip unless the service is bad, and my boyfriend always complains because he wants to know when it jumped from 15% to 20%. 20% is easier to figure out, anyway. (boooo math!:p)

haha yeah, nothing more pathetic than seeing rich guys driving solid cars yet not tipping at all....but don't worry, they'll get their come'often.