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	$243.57	9.126%	$265.7982	$265.80	$265.80	$265.80
Purchase #2	$38.66	10.359%	$42.6648	$42.66	$42.65	$42.70
Purchase #3	$48.27	4.507%	$50.4455	$50.45	$50.45	$50.40
Purchase #4	$83.65	7.305%	$89.7606	$89.76	$89.75	$89.80
Purchase #5	$220.80	4.189%	$230.0493	$230.05	$230.05	$230.00
Purchase #6	$124.70	7.843%	$134.4802	$134.48	$134.50	$134.50
Purchase #7	$184.64	6.662%	$196.9407	$196.94	$196.95	$196.90
7 purchase totals =	$944.29		$1,010.1393	$1,010.14	$1,010.15	$1,010.10