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	$214.99	12.344%	$241.5284	$241.53	$241.55	$241.50
Purchase #2	$68.26	12.303%	$76.658	$76.66	$76.65	$76.70
Purchase #3	$65.83	8.333%	$71.3156	$71.32	$71.30	$71.30
Purchase #4	$203.81	11.268%	$226.7753	$226.78	$226.80	$226.80
Purchase #5	$92.58	7.862%	$99.8586	$99.86	$99.85	$99.90
Purchase #6	$242.60	6.611%	$258.6383	$258.64	$258.65	$258.60
Purchase #7	$60.53	11.489%	$67.4843	$67.48	$67.50	$67.50
7 purchase totals =	$948.60		$1,042.2585	$1,042.27	$1,042.30	$1,042.30