If you want to test this, you can use my fullprecision branch of Gavin's test network.
http://github.com/EricJ2190/bitcoin-git/tree/fullprecisionI believe the normal client simply truncates the values whenever they are displayed.
string FormatMoney(int64 n, bool fPlus)
{
n /= CENT;
string str = strprintf("%"PRI64d".%02"PRI64d, (n > 0 ? n : -n)/100, (n > 0 ? n : -n)%100);
for (int i = 6; i < str.size(); i += 4)
if (isdigit(str[str.size() - i - 1]))
str.insert(str.size() - i, 1, ',');
if (n < 0)
str.insert((unsigned int)0, 1, '-');
else if (fPlus && n > 0)
str.insert((unsigned int)0, 1, '+');
return str;
}
