Looking at the code, the rounding is being done by the fetch, not after populating the local variables, so the above solution would be too late.

How about converting the data to string in situ before the fetch using the DBMS, i.e. change the line assigning $sql to

my $sql = 'select MF_FUND_CLASS,
                  MF_START_DATE,
                  MF_END_DATE,
                  convert( char(64), MF_ROR )
               from T_LIMF_MRD_FUND_ROR';
[download]

The above example is for Sybase. For mysql, the parameters to the convert function are in the reversed order.