0.5 ex?

I have been seeing price like 0.5ex on poe trade days ago. but now seems all at least 1ex? I tried to list on item myself as 0.5 ex but it still shows up as 1 ex on poe trade.
So how do I list something cheaper than a ex? I tried to list like 1 regal or 1 alch but poe trade always list my item behind the ton of 1 ex item, so other player could never see my item by default (unless in option they specificly search by regal or alch which lots of people wont do)

I would also like to know.