It is easier to round. Most teachers would like you to round each value to the nearest tenth.
I had no idea what was being asked for the other side(y axis) of the graph... Assuming you are in the beginning of learning graphs. Think of it as a number line on each side. And when you get the bottom numbers the points make an invisible line up into the graph where the intercept is where the point it. (that is cordiance points btw) I will follow you so I can help you with future problems. :)
