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	$66.58	7.434%	$71.5296	$71.53	$71.55	$71.50
Purchase #2	$64.31	7.492%	$69.1281	$69.13	$69.15	$69.10
Purchase #3	$205.91	7.246%	$220.8302	$220.83	$220.85	$220.80
Purchase #4	$143.96	3.177%	$148.5336	$148.53	$148.55	$148.50
Purchase #5	$142.93	11.165%	$158.8881	$158.89	$158.90	$158.90
Purchase #6	$139.94	7.563%	$150.5237	$150.52	$150.50	$150.50
Purchase #7	$205.91	11.606%	$229.8079	$229.81	$229.80	$229.80
7 purchase totals =	$969.54		$1,049.2412	$1,049.24	$1,049.30	$1,049.10