Explanation
The QUARTILE function is automatic, and will calculate the 1st quartile with an input of 1, the 2nd quartile with an input of 2, and the 3rd quartile with an input of 3. With an input of 0, quartile returns the minimum value in the data.
The trick in this case is to arrange the conditional formatting rules so that they run in the same direction. The first rule highlights values greater than the 3rd quartile. The second rule highlights values greater than the 2nd quartile, the 3rd rule highlights data greater than the 1st quartile, and the last rule highlights data greater than the minimum value.