There is no property setting to do this.
If you do not want to use the PrintToFit technique that sizes a bitmap, then you will have to do something else.
You can try zooming the grid during printing. Again, there is no property to do this yet, but you can do it from code. You can try to implement zooming on your own.
Here is a sample that just zooms a grid. You would have to implement this behavior while teh grid is being printed, maybe checking teh grid.PrintMode property to decide when to zoom things. Now depending upon exactly what you are doing in your grid, you may have to adjust other items. It would take some coding to implement this.