Can an iPhone 5 stream music through Bluetooth?

I have got a nexus fm transmitter and iPhone 5 so I could use it in my car (my car is very old and this is the only way)

I have got them paired, I am able to make phone calls and Siri through it, but when I play music, it comes through the iPhone speaker. It may be that I have to tweak some settings, but then I have read some people say that iPhones can't stream music over Bluetooth. Is this correct? Is it possible to stream music through Bluetooth?

Cheers