in Source/Charts/Utils/ChartUtils.swift [75:88]
func roundedToNextSignificant() -> Double
{
guard
!isInfinite,
!isNaN,
self != 0
else { return self }
let d = ceil(log10(self < 0 ? -self : self))
let pw = 1 - Int(d)
let magnitude = pow(10.0, Double(pw))
let shifted = (self * magnitude).rounded()
return shifted / magnitude
}