Whenever a tract of land shall be mapped and laid out by the owner showing lots and a street or streets on such lands and the map has been placed on file in the office of the county clerk or of the register of deeds of the county in which the lands are located and sales have been made of some of the lots, and when the street or streets have been treated by the municipality in which the streets are located as private property and assessed as such, the municipality subsequently treating the street or streets as fully dedicated and opening such street or streets without condemning the lands, may in its discretion return the taxes so paid without interest for a period not to exceed twenty years.