Fade Looped Audio at End of Project

Hello,

I have a background track that loops throughout my project, and I've set it up so that it plays at a lower volume than the narration on the screen.

I would like to have it so that at the very end of the project, the track fades rather than stopping abruptly. How can I edit my background audio so that it fades at the very end of the project, but doesn't impact the loop transitions earlier on?

Thank you!