Use of real values in anchor margin

Question

I was going through the QML documentation which says that the anchor margins can be **real** values.
e.g.

anchor
{
top: parent.top
topMargin: 10 // This is valid
left: parent.left
leftMargin: 80.45 // This is also valid
}

But somehow, the real value is getting rounded off to the nearest integer values. Then what is the real use of having a real value for margin?

In case, my UX designer is giving me a real value for margin, how I will be able to translate the same in the code? Or, there is no way to do the same in QML?