If you master a dance round with the a certain percentage of accuracy, you get an item.
There are two different items for each room.
To go to another room, just walk to a side of the Aquarium and look for arrows to the other rooms.
From the Aquarium you can either go down to Hillbilly and Hell or up to Skittles and Heaven.
List of items:
Heaven: Heavenly Drapes & Golden Sparkles 50% || 80%