This has probably already been settled by now but here's the logic according to me. But you need to get a lawyer's opinion just to make sure.
If you sold the house outright for $270,000 each one of you would get $54,000, which is one-fifth of $270,000.
Therefore for you to get the house, you should pay each of the other four $54,000. Four times 54,000 is 216 - so you are correct.
Another way of looking at it is for you to buy the house outright from the trust for $270,000. Then the trust would pay each one of the five, including you, $54,000 from the proceeds of the sale. The net effect would be that each of the others received their $54,000 and you would have obtained ownership of the house for $216,000.