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	$82.68	4.439%	$86.3502	$86.35	$86.35	$86.40
Purchase #2	$142.45	3.602%	$147.581	$147.58	$147.60	$147.60
Purchase #3	$169.54	5.536%	$178.9257	$178.93	$178.95	$178.90
Purchase #4	$79.26	3.298%	$81.874	$81.87	$81.85	$81.90
Purchase #5	$79.33	3.707%	$82.2708	$82.27	$82.25	$82.30
Purchase #6	$143.60	5.731%	$151.8297	$151.83	$151.85	$151.80
Purchase #7	$146.51	8.276%	$158.6352	$158.64	$158.65	$158.60
7 purchase totals =	$843.37		$887.4666	$887.47	$887.50	$887.50