Reimbursement from 529 plan for off-campus room and board - if the college lists separate COA for room and board does that limit the tax-free reimbursement for each?

My grandson will be attending a junior college full time.  He will be staying off-campus.  The college's COA lists $5,757 for room and $5,757 for food.  If the actual rent is higher than $5757, but no reimbursement is sought for the food, would the distribution of $8,000 for rent alone all be nontaxable?  or only up to $5757?