What do you mean by "authenticity"? Will you need it in a court case? If so, do not laminate it, that will make it hard to examine if its authenticity is questioned. If you think it has historic value (signed by George Washington or something) do not laminate it, but have it professionally framed. In other words, authenticity is diminished by laminating a document. Don't do it.
Laminating it will not harm its authenticity in any way. Instead of laminating the tax receipt, scan it and remain with two copies. Old taxi receipts can sometimes be very effective in court cases as prove of evidence.