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	$87.94	8.805%	$95.6831	$95.68	$95.70	$95.70
Purchase #2	$220.86	4.636%	$231.0991	$231.10	$231.10	$231.10
Purchase #3	$103.78	8.375%	$112.4716	$112.47	$112.45	$112.50
Purchase #4	$202.77	10.216%	$223.485	$223.49	$223.50	$223.50
Purchase #5	$34.77	10.823%	$38.5332	$38.53	$38.55	$38.50
Purchase #6	$225.45	12.519%	$253.6741	$253.67	$253.65	$253.70
Purchase #7	$48.89	7.237%	$52.4282	$52.43	$52.45	$52.40
7 purchase totals =	$924.46		$1,007.3743	$1,007.37	$1,007.40	$1,007.40