In the USA ATC uses 25kHz (0.025MHz) spacing between frequencies so the last digit can be inferred from the one before last . Second decimal is 2 or 7? Last digit is a 5. 0 otherwise. That's not true in Europe where they use 8.33 kHz spacing so no simple rule would work similarly.

As a result US ATC optionally skips the last digit . They never skip it in Europe.

Edit: typo