Подсчет суммы в таблице (неверно считает)

   int n=2;
   String FieldName = DBGrid1->SelectedField->FieldName;
   float sum=0;
   Table1->First();
   while (!Table1->Eof)
   {
    sum=sum+Table1->FieldByName(FieldName)->AsFloat;
    Table1->Next();
   }
 
   LabelSum->Caption=FloatToStrF(sum,ffNumber,8,2)+" Грн";
   LabelCout->Caption=IntToStr(Table1->RecordCount)+" Строк";

int n=2;
   String FieldName = DBGrid1->SelectedField->FieldName;
   float sum=0;
   Table1->First();
   while (!Table1->Eof)
   {
    sum=sum+Table1->FieldByName(FieldName)->AsFloat;
   [COLOR=red] sum=floor(sum*pow10(n)+0.5)*pow10(-n);[/COLOR]
    Table1->Next();
   }
LabelSum->Caption=FloatToStrF(sum,ffNumber,8,2)+" Ãðí.";
   LabelCout->Caption=IntToStr(Table1->RecordCount)+" ñòðîê";

double MathRound(double num, int precision)
{
  AnsiString s, number = FloatToStr(num);
  bool sign = false;
  double k;
  int pos = number.Pos('.');
  int len = number.Length();
  if ((pos == 0) || ((len - pos) <= precision)) return num;
  AnsiString prom = number.SubString(1, 1);
  if (prom == '-') sign = true;
  s = number.SubString(pos+precision+1, 1);
  int i = StrToInt(s);
  if (i >= 5){
   if (sign)
     k = floor(num*Power(10, precision))/Power(10, precision);
   else
     k = ceil(num*Power(10, precision))/Power(10, precision);
  }else{
   if (!sign)
     k = floor(num*Power(10, precision))/Power(10, precision);
   else
     k = ceil(num*Power(10, precision))/Power(10, precision);
  }
  return k;
}

Query->Close();
Query->SQL->Clear();
Query->SQL->Text=("Select SUM (SUMA) AS Result FROM CARDw");
Query->Open();