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	$31.27	11.357%	$34.8213	$34.82	$34.80	$34.80
Purchase #2	$19.25	10.722%	$21.314	$21.31	$21.30	$21.30
Purchase #3	$184.38	11.643%	$205.8474	$205.85	$205.85	$205.80
Purchase #4	$68.84	4.687%	$72.0665	$72.07	$72.05	$72.10
Purchase #5	$204.43	3.318%	$211.213	$211.21	$211.20	$211.20
Purchase #6	$238.77	6.823%	$255.0613	$255.06	$255.05	$255.10
Purchase #7	$229.93	13.804%	$261.6695	$261.67	$261.65	$261.70
7 purchase totals =	$976.87		$1,061.9930	$1,061.99	$1,061.90	$1,062.00