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	$11.84	4.335%	$12.3533	$12.35	$12.35	$12.40
Purchase #2	$30.27	3.670%	$31.3809	$31.38	$31.40	$31.40
Purchase #3	$88.91	6.854%	$95.0039	$95.00	$95.00	$95.00
Purchase #4	$100.65	3.196%	$103.8668	$103.87	$103.85	$103.90
Purchase #5	$124.95	4.460%	$130.5228	$130.52	$130.50	$130.50
Purchase #6	$229.40	5.395%	$241.7761	$241.78	$241.80	$241.80
Purchase #7	$239.87	12.828%	$270.6405	$270.64	$270.65	$270.60
7 purchase totals =	$825.89		$885.5443	$885.54	$885.55	$885.60