Rounding up and down heading readings

[Cecco]

Hi,

When asked by ATC e.g "what´s your present heading", I usually round up or down the figure e.g if it´s hdg 142, I would say hdg 140; likewiese hdg 143 would be rounded up to hdg 145. Furthermore, I never heard pilots or ATC stating a heading other than with a -0 or -5 at the end.

I am wondering, however, why doesn´t ATC need the exact heading or to put it another way, why rounding up or down to the nearest -5 or -0 is tolerated? What do you see on your radar screen?

Cheers

Cecco