Round date to 10 minutes interval

Question

I have a DATE column that I want to round to the next-lower 10 minute interval in a query (see example below).

I managed to do it by truncating the seconds

Answer 1

select
  trunc(sysdate, 'mi')
  - numtodsinterval(mod(EXTRACT(minute FROM cast(sysdate as timestamp)), 10), 'minute')
from dual;

or even

select
  trunc(sysdate, 'mi')
  - mod(EXTRACT(minute FROM cast(sysdate as timestamp)), 10) / (24 * 60)
from dual;