How to avoid 1.23 decimal point uneven unit value in Photoshop?

When I drag the icon to left and to right in paragraph panel of Photoshop for tweaking the paragraph styling, changing the value of space before and after paragraph, I get uneven unit value like 1.23 with decimal point. This is really annoyed to me. Do you know how to turn it off so it will get, for examples, 1, 2, 3, 10, 20, 30 values only?

And is there a shortcut to change the value to 5px, 10px, 20px, etc...?

Thanks in advanced.