OpenMRS does not yet support full multitenancy. I have seen some implementations in Nigeria (@ggomez) that are using work arounds like the Location Based Access Control module.
@angshuonline is of the opinion that a true SaaS Maturity Model 4 with multi-tenancy of single DBs are not desirable always, in this age where infra is cheap and dynamic provisioning is very much achievable. He goes ahead and gives some details here: Bahmni as Multi-Tenant SAAS solution