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	$187.53	4.849%	$196.6233	$196.62	$196.60	$196.60
Purchase #2	$143.61	11.212%	$159.7116	$159.71	$159.70	$159.70
Purchase #3	$44.70	12.857%	$50.4471	$50.45	$50.45	$50.40
Purchase #4	$134.98	3.622%	$139.869	$139.87	$139.85	$139.90
Purchase #5	$183.48	9.152%	$200.2721	$200.27	$200.25	$200.30
Purchase #6	$155.79	4.131%	$162.2257	$162.23	$162.25	$162.20
Purchase #7	$125.77	8.500%	$136.4605	$136.46	$136.45	$136.50
7 purchase totals =	$975.86		$1,045.6093	$1,045.61	$1,045.55	$1,045.60