NO. Roadie’s Terms and Conditions specifically prohibit a Driver from soliciting tips or additional compensation from Gig recipients or Senders. Roadie is an "on-the-way" delivery service. This means that the payment for a Gig is based on the Driver already heading in the delivery direction. Senders are given the ability to add a little extra to a Gig if they so choose, but they’re not expected to pay anything outside of the quote Roadie gives them.
Drivers who regularly follow the standard process are usually matched over someone who requests a higher payout for the delivery.
Keep in mind that if a Gig doesn’t seem worth it you are totally free to pass on it and wait for the next one that fits your plans and pays what you want. Drivers aren’t required to take a certain number or percentage of Gigs, so just wait for the right Gig!