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	$95.46	8.369%	$103.449	$103.45	$103.45	$103.40
Purchase #2	$11.87	10.472%	$13.113	$13.11	$13.10	$13.10
Purchase #3	$101.43	10.773%	$112.3571	$112.36	$112.35	$112.40
Purchase #4	$74.67	6.483%	$79.5109	$79.51	$79.50	$79.50
Purchase #5	$93.32	12.821%	$105.2846	$105.28	$105.30	$105.30
Purchase #6	$226.71	8.196%	$245.2912	$245.29	$245.30	$245.30
Purchase #7	$99.80	5.766%	$105.5545	$105.55	$105.55	$105.60
7 purchase totals =	$703.26		$764.5603	$764.55	$764.55	$764.60