Self-Exlpanitory, I would love to know!
>As of X & Y, if you have one of the parents hold the Destiny Knot item, then 5 IVs total from either parent will be guaranteed to be transferred - Serebii
So in short Yes, actually it will pass down 5 Ivs
Yes, it passes down 5 IVs from the holder down to the egg. 3 IVs in past Generations.