The docstring for round contains some clues that may be useful

round(dt::TimeType, p::Period, [r::RoundingMode]) -> TimeType
Return the Date or DateTime nearest to dt at resolution p. By default (RoundNearestTiesUp), ties (e.g., rounding
9:30 to the nearest hour) will be rounded up.
For convenience, p may be a type instead of a value: round(dt, Dates.Hour) is a shortcut for round(dt,
Dates.Hour(1)).
julia> round(Date(1985, 8, 16), Dates.Month)
1985-08-01
julia> round(DateTime(2013, 2, 13, 0, 31, 20), Dates.Minute(15))
2013-02-13T00:30:00
julia> round(DateTime(2016, 8, 6, 12, 0, 0), Dates.Day)
2016-08-07T00:00:00
Valid rounding modes for round(::TimeType, ::Period, ::RoundingMode) are RoundNearestTiesUp (default), RoundDown
(floor), and RoundUp (ceil).
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round(x::Period, precision::T, [r::RoundingMode]) where T <: Union{TimePeriod, Week, Day} -> T
Round x to the nearest multiple of precision. If x and precision are different subtypes of Period, the return value
will have the same type as precision. By default (RoundNearestTiesUp), ties (e.g., rounding 90 minutes to the
nearest hour) will be rounded up.
For convenience, precision may be a type instead of a value: round(x, Dates.Hour) is a shortcut for round(x,
Dates.Hour(1)).
julia> round(Dates.Day(16), Dates.Week)
2 weeks
julia> round(Dates.Minute(44), Dates.Minute(15))
45 minutes
julia> round(Dates.Hour(36), Dates.Day)
2 days

I didn’t know this, is this new? And how is it different from apropos("round"), which returns lots more (in this case mostly unhelpful, I’d say…) hits?