If you end the auction early with a high bidder 
in place, the item is considered sold and the 
high bidder is the winner. You will be charged 
fees for this.

If you were to break or lose an item which you 
are auctioning (like you theorized), then you 
would need to cancel all the bids on the item and 
end the auction when there are no bidders. That 
is the only way to end an auction without being 
obligated to sell the item. (And in that case, 
yes, you would *not* be charged fees since the 
item did not sell.)

I think what you're thinking of is if there is a 
reserve on the item that is not met by the 
highest bidder. If a reserve is not met when the 
auction ends, even if there is a high bidder, the 
item is considered to be NOT sold -- you are not 
charged fees, and it is impossible to leave 
feedback for either party.

Many Sharp Smiles,
--Drac