Tor prevents that that the site you're accessing or anybody else knows where the request is coming from. So it protects your identity.
It does NOT provide protection against eavesdroppers as the data sent from the exit node to the actual server is not encrypted unless it was in the first place e.g. with https. But that shoud not matter if the data transmitted is not related to your identity.
When using tor for banking the only use is accordingly to prevent others from knowing that you're doing this. As you're revealing personal information that only works as long as you're using encryption (no eavesdropper on that sensitive information). You're bank obviously needs to know what you're doing.
Banking does not become significantly safer because of this.