Round time to the closest 20-minute interval?

I want to round a given time to its closest 20-mintue interval.

For example, if given the time below:

Note: 12:10 pm -> 12:20 pm, round up if it’s in the middle of the 20-min interval.

I have tried using the code from a similar thread, as shown below: (Rounding up to nearest 30 minutes in Python)

from datetime import datetime, timedelta

def ceil_dt(dt, delta):
    return dt + (datetime.min - dt) % delta

now = datetime(2023, 2, 24, 12, 21, 00)
print(now)    
print(ceil_dt(now, timedelta(minutes=20)))
#ts.round(freq='T') # minute

As you can see, the given time is 12:21:00, but the output is 12:40:00. Instead, I want 12:21:00 to round to 12:20:00. Eventually, the goal is apply this to a datetime column in pandas, let me know if there is an easier method. Thanks!

>Solution :

from datetime import datetime, timedelta

def round_dt(dt, delta):
    increase = (datetime.min - dt) % delta
    if increase < delta / 2:
        return dt + increase
    else:
        return dt + increase - delta

now = datetime(2023, 2, 24, 12, 21, 00)
print(now)    
print(round_dt(now, timedelta(minutes=20)))

to apply it to a dataframe column, you can use functools.partial and .apply