Any tips for convincing my parents to let me buy GTA 5.?

It really has nothing to do with your grades or being a good kid. I have no idea what GTA means, but if it's a violent video game, understand that your parents aren't saying no to be mean. It's tough raising a kid in today's world. Like you say, there's sex and violence and gore all around. It's possible that your mom and dad realize this, but they don't feel the need to perpetuate it on their television screen. They worry about things you can't even fathom, like that maybe you'll become desensitized to violence, etc.

When you are 18, you can do as you please and buy the game for yourself. But right now you are 15, and there are plenty of other things you can focus on. Go read a book or paddle a canoe.

As a parent and also a gamer I kind of agree with your parents. I love all the gta games but they are seriously awful haha.

You could make that argument and mention all those things you did here. But it has nothing to do with your grades and all that.

My boyfriend says he would threaten his parents and say his g.p.a will go down if he doesnt get it. I would just do what you would do or just say give me a week or a month to play this game that I will buy myself. If my grades go down or I do anything bad, then you can take this game and I will never play it again and I also will pay you the amount I paid for the game.... or pick your own punishment. They will most likely say no but it's a good argument when you're also so mature and smart so young.

Good luck ;)

You could let them be with you went you plays, while not ideal they will at least know your not doing stuff like going to the strip club