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	$223.75	13.445%	$253.8332	$253.83	$253.85	$253.80
Purchase #2	$119.71	7.717%	$128.948	$128.95	$128.95	$128.90
Purchase #3	$209.35	11.697%	$233.8377	$233.84	$233.85	$233.80
Purchase #4	$25.54	9.189%	$27.8869	$27.89	$27.90	$27.90
Purchase #5	$75.78	10.518%	$83.7505	$83.75	$83.75	$83.80
Purchase #6	$191.89	3.456%	$198.5217	$198.52	$198.50	$198.50
Purchase #7	$126.63	8.282%	$137.1175	$137.12	$137.10	$137.10
7 purchase totals =	$972.65		$1,063.8955	$1,063.90	$1,063.90	$1,063.80