Currency Exchange - Order completed but only bought one item??

This seems really silly..

If you place an order for 20 items at 15 chaos each, totalling 300 chaos.

It will keep the order in 'Order Listed' status and carry on buying items when available at that price.

If you place and order for 20 items, at 15.05 chaos each, totalling 301 chaos.

It will buy ONE item, and then say 'Order Completed' and will no longer buy any more items.

By the looks of things, the excess gold fee is returned, but this is pretty annoying if you create a listing, log off and come back hours later to just one item.

This is obviously because you cannot split an item, but then why are partial listings allowed when NO item in the game can be split to allow for this and you cannot guarantee that people will sell in multiples of X to allow for your '1.25' orders for example?

Surely it should say 'ratio not possible' or something? or maybe round up/down to make the ratio whole?