declare
  i number:=45.0;
  j number:=45.0000001;
begin
  if i-trunc(i) = 0 then  -- take care if anyone is integer
    i := i + 0.0000001;
  end if;
  if j-trunc(j) = 0 then
    j := j + 0.0000001;
  end if;
  if trunc(i) = trunc(j) and substr(rpad(i-trunc(i),7,'0'),2,7) = 
                        substr(rpad(j-trunc(j),7,'0'),2,7) then
    dbms_output.put_line('equal');
  else
    dbms_output.put_line('not equal');
  end if;
end;
/

declare
  i number :=45.66;
  j number:=45.6600009;
begin
  if trunc(i,6) = trunc(j,6) then
    dbms_output.put_line('equal');
  else
    dbms_output.put_line('not');
  end if;
end ;
/

MYDBA > select round(45.6673419,6), trunc(45.6673419,6) from dual;

ROUND(45.6673419,6) TRUNC(45.6673419,6)
------------------- -------------------
          45.667342           45.667341