Rounded Corners for the Crop options

Rounded corners are making a style comeback. And they are used all the time for retro styles. But I need to put something in a rounded box, there is no way to do it. I've watched every video on youtube claiming to have a solution, using roughen edges, etc. Even the strange shap layers in premiere don't have rounded corners. 

Illustrator has it. After Effects has it. Why doesn't premiere? Because they want me to interrupt my workflow and jump into After Effects when I'm still editing and figuring out timings? No I can't use a track matte, because I have to move things around via a nest etc. 

Rounded cornes via the crop tool. That's it. We can make this happen.