i have this customer, nice lady, nice husband, no complaints, good to work with. everytime i send her a bill, she pays the subtotal with a money order, and the sales tax by personal check. AND.... she's always $2-$3 off (less). i can't figure her out, she does this every single month. it's none of my business, so i don't ask (about recieving 2 checks every month), but the short 2-3 bucks is. i just add it to her next bill. any idea what would make someone pay by money order for subtotal, and personal check for sales tax?