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	$62.26	8.267%	$67.407	$67.41	$67.40	$67.40
Purchase #2	$83.28	6.621%	$88.794	$88.79	$88.80	$88.80
Purchase #3	$12.33	9.733%	$13.5301	$13.53	$13.55	$13.50
Purchase #4	$194.30	12.707%	$218.9897	$218.99	$219.00	$219.00
Purchase #5	$248.28	12.536%	$279.4044	$279.40	$279.40	$279.40
Purchase #6	$194.30	3.391%	$200.8887	$200.89	$200.90	$200.90
Purchase #7	$99.29	4.155%	$103.4155	$103.42	$103.40	$103.40
7 purchase totals =	$894.04		$972.4294	$972.43	$972.45	$972.40