To me cash and gift serve the same purpose so it really doesnt matter which I receive or give. It depends on the age of the person if it for a small child I rather give a gift card to a certain store. But other than that it just cash or gift card doesnt matter
In my opinion, giving cash as a gift depends on the kind of person you are interacting with. I had lent some money to my friend and instead of returning the money, my friend thought about gifting a music system. I would have preferred to have the money back instead of the music systems as I will be on a tight budget many a times. Although the music system had costed him much more than what I had given him, it was of no use to me as I was not the kind of person who listens to music very often. I think it is always better to give cash as a gift to other people as only the receiver knows what exactly he would want to buy and if you give them the money they would be way too happy. However, I have met a lot of people who find it weird to give money to others, although I never understood the reason very thoroughly.
I have never know anyone to turn down cash as a gift. I know that I wouldn't turn it down. I don't think that $5 would be enough for a teenager now. When I was a kid, $5 went a long way. $5 doesn't even buy lunch at a decent fast food restaurant. My niece will turn 13 years old next year and I'm already thinking about what to buy her. It was a lot easier to shop for her when she was younger.
A thirteen year old would probably roll their eyes at you if you offered them a $5 as a present. Ten to Fifteen dollars would be adequate. Most of the games thirteen year olds play cost much more, but there are still plenty of smaller things they could buy. Or maybe they could use it to save for something bigger. Giving a consecutive amount for that purpose could be a useful way to use money as a gift.