Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$222.88	13.532%	$253.0401	$253.04	$253.05	$253.00
Purchase #2	$92.52	13.585%	$105.0888	$105.09	$105.10	$105.10
Purchase #3	$212.86	13.498%	$241.5918	$241.59	$241.60	$241.60
Purchase #4	$248.91	8.674%	$270.5005	$270.50	$270.50	$270.50
Purchase #5	$65.55	11.249%	$72.9237	$72.92	$72.90	$72.90
Purchase #6	$132.62	4.355%	$138.3956	$138.40	$138.40	$138.40
Purchase #7	$76.93	11.254%	$85.5877	$85.59	$85.60	$85.60
7 purchase totals =	$1,052.27		$1,167.1282	$1,167.13	$1,167.15	$1,167.10