Hugh,
Yes, this is true. Most banks do not have any halves on hand. It’s been a few years since they have even been minted for circulation. Ordering a box of $500 is the minimum, and they will expect you to take the box. Some banks even have $1000 min to order. Some banks do not want to be bothered at all. Most likely a bank that you [regularly] bank with will order them, and then you have to dispose [of them]! The bank you order them from will not want them back. Maybe the first time, but not thereafter. So spending them [back into circulation] is a way to use them. That’s just my experience?. – DSV