weekday function

I have data on a daily basis.
Want to group data by the week starting on Saturday.
When I use the weekday function with return type 16, I get these values in return

27-Feb-16 Sat 20-Feb-16
28-Feb-16 Sun 27-Feb-16
29-Feb-16 Mon 27-Feb-16
01-Mar-16 Tue 27-Feb-16
02-Mar-16 Wed 27-Feb-16
03-Mar-16 Thu 27-Feb-16
04-Mar-16 Fri 27-Feb-16
05-Mar-16 Sat 27-Feb-16
06-Mar-16 Sun 05-Mar-16
07-Mar-16 Mon 05-Mar-16
08-Mar-16 Tue 05-Mar-16
09-Mar-16 Wed 05-Mar-16
10-Mar-16 Thu 05-Mar-16
11-Mar-16 Fri 05-Mar-16

I was expecting for 2/27 to be returned for 2/27, but it returns 2/26.
How can I fix this?