Look into a dutch auction - multiply the various bid amounts by the number of people that will pay that, and take the highest product - which all successful bid

Look into a dutch auction - multiply the various bid amounts by the number of people that will pay that, and take the highest product - which all successful bidders pay. For example, it's better to fill 25 offices at $10 per month than 30 at $5. From a fairness perspective all winners are paying the same amount too, and any empty space can be rented out shorter term for larger amounts for inevitable short-term overflow needs.