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	$194.28	8.838%	$211.4505	$211.45	$211.45	$211.50
Purchase #2	$57.93	5.723%	$61.2453	$61.25	$61.25	$61.20
Purchase #3	$151.98	10.491%	$167.9242	$167.92	$167.90	$167.90
Purchase #4	$247.65	4.167%	$257.9696	$257.97	$257.95	$258.00
Purchase #5	$53.68	13.353%	$60.8479	$60.85	$60.85	$60.80
Purchase #6	$166.42	9.115%	$181.5892	$181.59	$181.60	$181.60
Purchase #7	$227.44	12.528%	$255.9337	$255.93	$255.95	$255.90
7 purchase totals =	$1,099.38		$1,196.9604	$1,196.96	$1,196.95	$1,196.90