Round time up/down using DATETIME()

[Tritonos_Gruppe]

I am trying to round up or down time to whole 30 min but can not figure out what I am doing wrong in my formula.

DATETIME(NOW())(
DATETIME(TIMENOW())()(HOUR(TIMENOW()-“0:00”)+“1:00”)-
IFS(
MINUTE(NOW()-“0:00”)>45,“0:00”,
MINUTE(NOW()-“0:00”)>30,“0:30”,
MINUTE(NOW()-“0:00”)>15,“0:30”,
MINUTE(NOW()-“0:00”)>0,“0:30”
)
)
OR(
MINUTE([Time In]-“0:00”)=0,
MINUTE([Time In]-“0:00”)=30,
MINUTE([Time In]-“0:00”)=30,
MINUTE([Time In]-“0:00”)=30
)

Any help would be appreciated.