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	$222.56	4.846%	$233.3453	$233.35	$233.35	$233.30
Purchase #2	$65.75	9.283%	$71.8536	$71.85	$71.85	$71.90
Purchase #3	$49.81	4.865%	$52.2333	$52.23	$52.25	$52.20
Purchase #4	$105.27	5.471%	$111.0293	$111.03	$111.05	$111.00
Purchase #5	$89.57	5.234%	$94.2581	$94.26	$94.25	$94.30
Purchase #6	$53.32	13.118%	$60.3145	$60.31	$60.30	$60.30
Purchase #7	$122.42	13.123%	$138.4852	$138.49	$138.50	$138.50
7 purchase totals =	$708.70		$761.5193	$761.52	$761.55	$761.50