Tenant is always responsible for the cleaning of his/her own apartment. In shared apartments the roommates are together responsible for the cleaning of the common areas (kitchen, bathroom, hall, possible living room). In addition to that every tenant is responsible for the cleaning of his/her own room.
According to the Act on Residential Leases the tenant shall look after the apartment carefully which also covers regular cleaning. To roommates in shared apartments TYS recommends a list, where weekly tasks like taking rubbish out and cleaning the toilet have been shared equally.
Read also about cleaning when moving out here.