These notifications are bundled together for some reason. So if I want to be notified when my subscriptions renew themselves, I have to also be notified of random games going on sale, too.
There's an app, and I'm sure others like it, called Tidy Panel that lets you block notifications based on the content they have. The free version let's you block a handful, but you need premium for unlimited. For you, the free might be enough.