R.I. Gen. Laws § 39-14-16: Posting of schedule of fares.

The owner of every taxicab or limited public motor vehicle shall post in a conspicuous place, in each of the taxicabs or limited public motor vehicles owned by him or her, a schedule of the fares to be collected from the passengers therein, and the schedule shall be so written and arranged that the passengers can readily determine the exact fare payable by them, and it shall be unlawful to collect any fare otherwise than as appearing on and determinable from the schedule.