Question

Is trunc and round the same with negative arguments?

       SQL> select round(123456.76,-4) from dual;

        ROUND(123456.76,-4)
         -------------------
         120000

         SQL> select trunc(123456.76,-4) from dual;

          TRUNC(123456.76,-4)
          -------------------
         120000

Answer 1

No, behavior depends on the value of the significant digit (the 3rd digit (the 3) is the significant one in your case, as it is below 5 round and trunc do the same )

try select trunc(125456.76,-4) from dual (result is 120000) vs select round(125456.76,-4) from dual (result is 130000). Now when the significant digit is 5 (or higher) the results of trunc and round differ.