Penny Utilization

In the course of pursuing my continuing years-long crusade to eliminate the penny I considered this afternoon that there must be a relationship between local per-capita utilization of pennies and the locale's sales tax rate. That is, a locale with a 6% sales tax would require four pennies to make change for a $1 transaction, while a locale with a 10% sales tax would use no pennies. Given that there isn't a uniform distribution of purchase prices, there must be some clustering that should result in observable penny utilization differences across states and cities.