Как научить Delphi делать правильное округление дробных чисел

function RoundStr(Zn: Real; kol_zn: Integer): Real;
var
  snl, s, s0, s1, s2: string;
  n, n1: Real;
  nn, i: Integer;
begin
  s := FloatToStr(Zn);
  if (Pos(',', s) > 0) and (Zn > 0) and
  (Length(Copy(s, Pos(',', s) + 1, length(s))) > kol_zn) then
  begin
    s0 := Copy(s, 1, Pos(',', s) + kol_zn - 1);
    s1 := Copy(s, 1, Pos(',', s) + kol_zn + 2);
    s2 := Copy(s1, Pos(',', s1) + kol_zn, Length(s1));
    n := StrToInt(s2) / 100;
    nn := Round(n);
    if nn >= 10 then
    begin
      snl := '0,';
      for i := 1 to kol_zn - 1 do
        snl := snl + '0';
      snl := snl + '1';
      n1 := StrToFloat(Copy(s, 1, Pos(',', s) + kol_zn)) + StrToFloat(snl);
      s := FloatToStr(n1);
      if Pos(',', s) > 0 then
        s1 := Copy(s, 1, Pos(',', s) + kol_zn);
    end
    else
      s1 := s0 + IntToStr(nn);
    if s1[Length(s1)] = ',' then
      s1 := s1 + '0';
    Result := StrToFloat(s1);
  end
  else
    Result := Zn;
end;

function RoundEx(X: Double; Precision: Integer ): Double;
{
Precision :
1 - до целых
10 - до десятых
100 - до сотых
...
}
var
  ScaledFractPart, Temp: Double;
begin
  ScaledFractPart := Frac(X) * Precision;
  Temp := Frac(ScaledFractPart);
  ScaledFractPart := Int(ScaledFractPart);
  if Temp >= 0.5 then
    ScaledFractPart := ScaledFractPart + 1;
  if Temp <= -0.5 then
    ScaledFractPart := ScaledFractPart - 1;
  RoundEx := Int(X) + ScaledFractPart / Precision;
end;