You do have 4 pockets, and there are 4 common American coins: pennies, nickels, dimes, and quarters. You could designate one pocket for each type of coin.
Alternately, you could make it a point of ONLY keeping one denomination of coin: only pennies, or only nickels, or only dimes, or only quarters. The others you could leave at the cash register or nearby.
Alternately, you could make it a point of only keeping coins that are easy to tell apart by "feel" in your pocket. Quarters and nickels are easy to mix up, but quarters and dimes are significantly different. You could keep all your quarters and dimes, and leave the nickels and pennies at the cash register or the tip jar. Then when pulling coins out of your pocket, you could play "pocket pool" for a couple seconds to select just the quarters or dimes that you need, and then pull those out of your pocket.