I am the author of Vanilo, and you're completely right. Vanilo atm (0.1) is a technology preview, and money handling is about to be settled until 0.2 (February 2018).
For client projects we've been using the moneyphp library, but that also fails with rounding when it comes to VAT rates like 19% or 27%. There is a "precise" branch on their github which we have successfully merged into an existing project and solved these nasty rounding issues.
Vanilo will most probably have that included soon.