On EBay, what is the best way to sell an item that you have multiple sizes of but its the same item?

I have a dress that is in 5 different sizes that I want to sell on ebay. It is the same exact dress except for the different sizes. Is it better to make 5 different auctions for all 5 sizes? Or is it better to just do one auction and say I have differnt sizes? How would that even work?? Has any one done this successfully. Can you tell me the most effective way to sell something like this?