Hey Saki, I like this change. When I was implementing additional rounding modes for the next PHP version I was initially struggling with the naming and this change will be helpful.
I have only one concern about the names `NegativeInfinity` and `PositiveInfinity`. They may be too formal from the user's perspective. As we already have functions `ceil` and `floor` it's more intuitive for developers to understand the logic of ceiling and floor rounding. But if voters will prefer those terms then it makes sense to change the constants implemented in PHP 8.4 (and thus not released yet) from `PHP_ROUND_(CEILING|FLOOR)` to `PHP_ROUND_(POSITIVE_INFINITY|NEGATIVE_INFINITY)` for the sake of consistency. Kind regards, Jorg
