Sixteenths rhymes with:
thirteenths, thirteenths, billionths, hyacinths, month's, months, months', ninths, sevenths, tenths, thirteenths
Sixteenths sounds like:
sediments, standex, standish, standouts, stands, statement's, statements, steinmetz, stendig, stentz, stints, student's, students, students', stunts, stuntz, systematic, systematics