Contractor or Home Owner?

[Robin L. Richards]

     Curious if a contractor receives a rebate using funds from the job to buy materials for that job does he get to keep the rebate? Does it belong to him if the cost of materials was included in his bid for the job? Does he get the refund on boxes when they are returned (boxes that held the the supplies) Does he get to keep the deposits when the equipment he rented is returned?