Allow negative decimal precision to round to 10s, 100s, etc

[jefffriesen]

Currently we have:

_('2.556').toNumber(1)
=> 2.6

What would be really nice would be able to round up beyond the decimal point. For example:

_(234).toNumber(-1)
=>230
_(234).toNumber(-2)
=>200

This is how d3 and some other library handle rounding. Currently trying it throws this error RangeError: toFixed() digits argument must be between 0 and 20

This could also work with _.numberFormat().

Does this seem like a good fit to this library?

[megawac]

+1 I'll make a pr for this tomorrow morning

[stoeffel]

+1 looks nice. I will look into this next week and review the PR from @megawac

[jefffriesen]

Any chance to work on this yet?
Thanks!

[jefffriesen]

This is great. Thanks!