select to_char(sysdate + 1/(24*60),'mi') from dual;

SQL> select to_char(sysdate,'MI') minute,
  2         to_char(sysdate+interval '1' minute,'MI') "MINUTE+1",
  3         to_char(sysdate-numtodsinterval(1,'MINUTE'),'MI') "MINUTE-1"
  4  from dual
  5  /
MI MI MI
-- -- --
55 56 54

1 row selected.

alter session set nls_date_format = 'dd-mon-rrrr hh24:mi:ss';

  1  select
  2   sysdate normal_granularity
  3  ,trunc(sysdate,'mi') minutes_granularity
  4  ,trunc(sysdate,'hh24') hours_granularity
  5  ,trunc(sysdate,'dd') days_granularity
  6  ,trunc(sysdate,'mm') months_granularity
  7  ,trunc(sysdate,'rrrr') years_granularity
  8* from dual
SQL> /

NORMAL_GRANULARITY   MINUTES_GRANULARITY  HOURS_GRANULARITY    DAYS_GRANULARITY     MONTHS_GRANULARITY   YEARS_GRANULARITY
-------------------- -------------------- -------------------- -------------------- -------------------- --------------------
14-sep-2009 23:57:44 14-sep-2009 23:57:00 14-sep-2009 23:00:00 14-sep-2009 00:00:00 01-sep-2009 00:00:00 01-jan-2009 00:00:00

SQL>