5 property listings or 5 dates soliciting the same property?
5 separate rooms in one dwelling or 5 distinct addresses?
5 distinct addresses/units. Each property whether rented as a whole unit/house/condo or 1 to xx rooms only rented in one home is considered one of your rental properties.
If you stay under 5 it has many benefits. Schedule E rental income or Schedule C if you choice to detail out expenses (very useful if doing AirBnB’s or HomeAway). Not bound by ADA or FHA rules. At 5 properties or more you are considered a commerical business in almost all states, thus higher property taxes, more paperwork and tons of codes to follow.