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	$201.78	10.453%	$222.8721	$222.87	$222.85	$222.90
Purchase #2	$143.27	4.540%	$149.7745	$149.77	$149.75	$149.80
Purchase #3	$97.57	10.346%	$107.6646	$107.66	$107.65	$107.70
Purchase #4	$188.52	6.589%	$200.9416	$200.94	$200.95	$200.90
Purchase #5	$188.70	10.497%	$208.5078	$208.51	$208.50	$208.50
Purchase #6	$65.76	10.775%	$72.8456	$72.85	$72.85	$72.80
Purchase #7	$88.35	13.255%	$100.0608	$100.06	$100.05	$100.10
7 purchase totals =	$973.95		$1,062.6670	$1,062.66	$1,062.60	$1,062.70