Custom "Tips Field"

My website is an online pet supplies store and we offer a delivery service. One of our shipping methods is called "Delivery" so the customers can ask us to deliver the products on a specific date. I was wondering if it would be possible to add a payment field called "Tips For Our Drivers" where customers could add a gratuity to their total bill at the checkout page. Can anyone assist me on how I could make this possible? Thank you!

There is no option for that.
You would have to edit the views of the checkout and add some code to add an input box and then automatically add a "tip" product which would cost 1 cent and set its quantity to reflect the price entered by the user.