Your value for a Roman cubitus is incorrect. It is actually equivalent to 0.445m not 0.554m.
The answer to your question is 4.99cubiti or 5 cubiti (if rouded-off).
Here is why:
[tex]2.22m * \frac{1cubitus}{0.445m} \\ =\frac{2.22cubiti}{0.445} \\ 4.99cubiti[/tex]
If you round-off your answer then your answer will be 5 cubiti.
