My standard tip is 20%. I don't use DoorDash much (maybe once or twice in a lifetime) but when I did I tipped that amount. If it's a real small order I will bump it up to an amount that makes it worth the driver's while, so $2 if the item is $5. That's so little they are likely taking a loss on it - counting their time as money and knowing the shafting those people get from their "employer." In my state there's no "tipped employee" wage like many states have, which is like $2.13/hr. But they still don't get paid what they are worth.