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	$196.52	7.330%	$210.9249	$210.92	$210.90	$210.90
Purchase #2	$164.87	6.537%	$175.6476	$175.65	$175.65	$175.60
Purchase #3	$207.52	11.725%	$231.8517	$231.85	$231.85	$231.90
Purchase #4	$241.94	9.149%	$264.0751	$264.08	$264.10	$264.10
Purchase #5	$84.62	5.773%	$89.5051	$89.51	$89.50	$89.50
Purchase #6	$34.87	13.668%	$39.636	$39.64	$39.65	$39.60
Purchase #7	$128.98	13.865%	$146.8631	$146.86	$146.85	$146.90
7 purchase totals =	$1,059.32		$1,158.5035	$1,158.51	$1,158.50	$1,158.50