Perfect for practicing rounding in the ones through ten thousands place, Tiny Chicken Learns Rounding is a free app from Tap to Learn that focuses on this single skill. Apps that have multiple math skills are wonderful but I often like to direct my students to single skills apps (ex. reading a ruler. long division, place value, symmetry) to keep them focused or to reinforce a specific concept.
Teaching math on iPads? Check out my Common Core aligned bundle of iPad lesson plans!