I'm going to claim that a package that was delivered to my roommate wasn't delivered.
Why are you claiming that the package wasn't delivered?
I'm looking to be greedy, I'm broke I need that package.
It's wrong to claim that you did not received another person's mail, if you did. Hiding someone's mail is illegal and will have negative consequences.
It was in the box but it wasn't addressed to me directly, but I really want it.
It's wrong to take something that is not yours. If you need help financially, it would be best to ask your roommate to borrow money. Taking another person's mail is wrong.