Keywords:
### ** Examples round_hms(as_hms("12:34:56"), 5)
12:34:55
round_hms(as_hms("12:34:56"), 60)
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round_hms(as_hms("12:34:56.78"), 0.25)
12:34:56.75
round_hms(as_hms("12:34:56.78"), digits = 1)
12:34:56.8
round_hms(as_hms("12:34:56.78"), digits = -2)
12:35:00
trunc_hms(as_hms("12:34:56"), 60)
12:34:00