5 gallons is too small to keep a sorority in. They might be getting along "okay" now, but they will eventually fight.
I would highly suggest getting a 10 gallon and putting them in that. Make sure they have lots of hiding places and plants.
I'm sorry that this isn't want you wanted to hear, but this is the advice you'll get from everyone.
I agree with the others. Its cruel to have that many is such a small space. Also keep in mind that betta personalities change. Just like humans they can get PMS and go nuts on day, so they really need their space.
You can rarely trust what a pet store employee says because they usually don't know much about bettas. You need a 10G tank for a female sorority. Do you have some extra bowls or tanks? I would take all of them out or try to divide them until you can get a 10G. Like New2Bettas said, they might be getting along now, but that can change in a heartbeat.
I agree, you need a lot more space for them. That's too small for that many girls. Never, ever trust the pet store. Maybe this sounds paranoid but I swear, they just want to overcrowd your tank, make your fish sick and ensure your continued business for meds and new fish. They need at least 10 gallons.
Well what I've decided to do tomorrow is, I've got a 110litre (about 25 gallons) tank with other various fish in, im going to return some of the fish that are not compatible & keep ones in the tank such as 4xzebra danios, 6x neon tetra, 4xrummy nose tetras, 2x panda corys & 2xcooli loaches & move my female siamese into that tank. That way there should be enough room & room for more......agree??