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	$91.43	4.639%	$95.6714	$95.67	$95.65	$95.70
Purchase #2	$28.93	13.240%	$32.7603	$32.76	$32.75	$32.80
Purchase #3	$85.45	3.359%	$88.3203	$88.32	$88.30	$88.30
Purchase #4	$155.51	8.690%	$169.0238	$169.02	$169.00	$169.00
Purchase #5	$103.53	7.865%	$111.6726	$111.67	$111.65	$111.70
Purchase #6	$22.78	11.315%	$25.3576	$25.36	$25.35	$25.40
Purchase #7	$11.65	8.414%	$12.6302	$12.63	$12.65	$12.60
7 purchase totals =	$499.28		$535.4362	$535.43	$535.35	$535.50