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	$208.82	8.833%	$227.2651	$227.27	$227.25	$227.30
Purchase #2	$233.61	4.329%	$243.723	$243.72	$243.70	$243.70
Purchase #3	$83.80	6.478%	$89.2286	$89.23	$89.25	$89.20
Purchase #4	$38.76	4.698%	$40.5809	$40.58	$40.60	$40.60
Purchase #5	$53.72	10.146%	$59.1704	$59.17	$59.15	$59.20
Purchase #6	$189.60	5.279%	$199.609	$199.61	$199.60	$199.60
Purchase #7	$93.65	11.500%	$104.4198	$104.42	$104.40	$104.40
7 purchase totals =	$901.96		$963.9968	$964.00	$963.95	$964.00