Input-Number: Fix precision problem (#15292)

[susiwen8]

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Replace toFixed() by Math.round(), because toFixed() follow Banker's Round
https://blog.csdn.net/fjnpysh/article/details/79077997

Close #15292

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[wacky6]

Does it really matter?

IEEE 754 float points won't correctly reflect human's definition of precision / number of decimal places anyway.

For reference:

• Inconsistent rounding of significant digits d3/d3-format#27
• https://www.ecma-international.org/ecma-262/6.0/#sec-number.prototype.tofixed

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And, JavaScript spec says nothing about Banker's Round. Please refer to ECMAScript spec instead of CSDN articles.

[susiwen8]

@wacky6 Well, someone point out this issue, so for some people it matter.

I did some test in Chrome dev tool, under toFixed() case, if the number before 5 is odd it will add 1, even number won't add 1.
4.115 -> 4.12
4.125 -> 4.12
4.135 -> 4.14
4.145 -> 4.14

From ECMAScript or MDN documents, there is no prove to support 'banker's round', but I look through some example those had same problem with toFixed() precision, they all suggest to use Math.round() to avoid this problem

[susiwen8]

Hi @wacky6 have you considered this?