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	$59.25	11.323%	$65.9589	$65.96	$65.95	$66.00
Purchase #2	$21.68	11.804%	$24.2391	$24.24	$24.25	$24.20
Purchase #3	$104.96	6.143%	$111.4077	$111.41	$111.40	$111.40
Purchase #4	$106.70	5.245%	$112.2964	$112.30	$112.30	$112.30
Purchase #5	$92.51	7.523%	$99.4695	$99.47	$99.45	$99.50
Purchase #6	$50.92	3.317%	$52.609	$52.61	$52.60	$52.60
Purchase #7	$243.84	9.124%	$266.088	$266.09	$266.10	$266.10
7 purchase totals =	$679.86		$732.0686	$732.08	$732.05	$732.10