I looked for information on typecasting in the awk/nawk/gawk man pages but found none but apparently it works and it supported even in the ancient 'awk' that Solaris has by...
I had a person bring an interesting problem to me that appears to involve some sort of rounding inside awk. I've verified this with awk and nawk on Solaris as well as with gawk 3.1.5 on a Linux box....