[FIX] web: Python-like rounding method
Javascript and Python handle the rounding of -x.5 differently.
In JS, `Math.round(-0.5)` is equal to `-0`.
In Python, `round(-0.5)` is equal to `-1`.
This will lead to inconsistencies between Python and Javascript, but it
can also lead to inconsistencies in the Javascript itself. Indeed, in
the POS, a refund to the client is entered as a negative number. For
example, `4.245` will be rounded to `4.25`, but a refund of `-4.245`
will be rounded to `-4.24`. The payment and the refund are not
consistent.
Sources:
- http://www.ecma-international.org/ecma-262/6.0/index.html#sec-math.round
- https://docs.python.org/2/library/functions.html#round
- https://en.wikipedia.org/wiki/Rounding#Round_half_up
Fixes #9249
opw-653034
Nicolas Martinelli
ea2c80cad0