"Customers can leave a tip when they check out or after the delivery is completed. 100% of tips are yours on top of base pay and promotions. The amount DoorDash pays will never vary based on the tip amount. For example, for two identical deliveries where one customer leaves a $3 tip and another customer leaves a $6 tip, one Dasher will earn $3 more than the other."

https://help.doordash.com/dashers/s/article/How-is-Dasher-pa....