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	$197.49	13.280%	$223.7167	$223.72	$223.70	$223.70
Purchase #2	$94.72	13.446%	$107.4561	$107.46	$107.45	$107.50
Purchase #3	$193.94	10.473%	$214.2513	$214.25	$214.25	$214.30
Purchase #4	$225.81	13.153%	$255.5108	$255.51	$255.50	$255.50
Purchase #5	$66.73	11.672%	$74.5187	$74.52	$74.50	$74.50
Purchase #6	$77.64	5.478%	$81.8931	$81.89	$81.90	$81.90
Purchase #7	$95.92	10.114%	$105.6213	$105.62	$105.60	$105.60
7 purchase totals =	$952.25		$1,062.9680	$1,062.97	$1,062.90	$1,063.00