The transfer, trading, or selling of ration tickets would have defeated the purpose of the system, which was to reduce demand for rationed items without increasing the amount of money required to buy them. Thus, in the rationing system adopted by the US during World War II, as well as in every other rationing system I have encountered, the transfer, trading, or selling of ration tickets was against the law.

This article does a good job of explaining how the system worked, and the many workarounds that people used to get the items that they wanted despite rationing.

https://fee.org/articles/the-two-price-system-us-rationing-during-world-war-ii/