Scale behavior broken?

[Express]

I've been trying to scale my sprites but they are not coming out correctly. The math seems to be broken in the scale function.

For instance I have the following function:

    def setHeight(self, height):

        self._realHeight = height

        self.scale_y = height / self.texture.height 

Setting it to anything other than something divisible by 5 will not work. If I try to scale_y to 1.2 it becomes 1.20000004768. 1.8 becomes 1.79999995232. While it may not seem like an issue, it is, as things no longer line up. Is there any way around this? I want to set my sprites at a specific width / height.