Homeschool Math
Homeschool Math: Basics of Percent
Video instructional activity [8:11] explains the basic concept of percents. Provides numerous problems for students to practice what they've learned.
Yale University
Yale New Haven Teachers Institute: Solving Problems "By the Hundreds"
The Yale-New Haven Teachers Institute site contains various math exercises relating to percentage and consumer-related problems. An explanation of sales tax, a related problem and answer are given.