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	$32.88	5.425%	$34.6637	$34.66	$34.65	$34.70
Purchase #2	$103.82	7.268%	$111.3656	$111.37	$111.35	$111.40
Purchase #3	$94.68	5.728%	$100.1033	$100.10	$100.10	$100.10
Purchase #4	$217.86	5.472%	$229.7813	$229.78	$229.80	$229.80
Purchase #5	$226.56	3.513%	$234.5191	$234.52	$234.50	$234.50
Purchase #6	$139.38	6.108%	$147.8933	$147.89	$147.90	$147.90
Purchase #7	$98.96	11.596%	$110.4354	$110.44	$110.45	$110.40
7 purchase totals =	$914.14		$968.7617	$968.76	$968.75	$968.80