Did you try it?
I shore did.
I get a warning
That warning came from Perl - the subroutine simply assumed you wanted to round the number zero - an undefined value was coerced to zero in context.

In reply to Re^2: Math::Round::Var::round() takes no action when a number is not supplied by metaperl
in thread Math::Round::Var::round() takes no action when a number is not supplied by metaperl

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