>x = '$20,650.000000000000000000'
>x3 = Substr(x1,1,at('.',x1)+4) && gives '$20650.0000'

Is there any reason to start with 18 decimal places?

Even in an engineering application, most equipment is incapable of measuring much beyond 8 decimal places. In a currency application, 4 decimal places should be sufficient to calculate the amount of money added to my check after this last salary increase. ;)

Anyway, that's just my $0.020000000000000000 worth.