529 plan - If the school lists housing and food separately on the COA for off campus, can the total be combined?

We have a 529 and this will be my sons first year living off campus. If the school splits out housing and food separately in their published COA, can the total be combined? I ask because my kid’s rent exceeds the published amount for housing, but his food costs are much less than the COA. So combined his room and board is less than the COA, but his housing exceeds. We’re keeping receipts for everything, but can we treat the COA allowance holistically or do we have to separate into separate buckets?