The Wikipedia article http://en.wikipedia.org/wiki/Nearest_integer_function mentions the following notation for the rounding or "nearest integer" function. (That is, the function that corresponds to the ordninary rounding where you go up if the fractional part is more than half, and down if less than half.)
$$ \lfloor x \rceil $$
This notation appeals to me because it is similar to the notation of $\lfloor x \rfloor$ for floor and $\lceil x \rceil$ for ceiling.
How common is this notation for rounding, and is there a reference for its first use?