You can absolutely refuse. You can also be taken to jail for obstruction. Part of the PRIVILEGE of driving includes that you must be properly licensed to do so, and be driving a vehicle with a current and proper registration. You can either allow the officer to check it during the stop, or you can present it to the judge after arrest. Point being, sure, you CAN refuse - but doing so can carry consequences. Whether or not those potential consequences are worth your exercise of saying "no", only you can evaluate. The place to challenge whether or not probable cause existed for the stop isn't at the roadside - you'll get your chance to argue about that issue in court, should you find the need to fail to comply with the officer's otherwise lawful order to present your license and registration.