Like most hospitality packages when placed in a situation w/ any thing more than "minimal" retail, Aloha will fail miserably. That explains why you are unhappy- it simply isn't designed for that.
We support and sell both environments where I work, and they have completely different needs, even though they are both essentially "cash registers".
Basically, a system like Aloha is going to be able to deal with stuff like tobacco, and some promotional items like hats and t-shirts... Stuff that isn't going to be returned or involved complicated scenarios that you are running into there.
Anyway, just a heads up that if you are planning to look into getting this system to do more and more, you are going to be more and more disappointed as time goes on.
You can reopen that servers check to refund something sold the same day, but again, this isn't a thorough way to address what you're asking (like if someone comes back tomorrow).