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	$88.43	8.280%	$95.752	$95.75	$95.75	$95.80
Purchase #2	$22.47	6.394%	$23.9067	$23.91	$23.90	$23.90
Purchase #3	$179.94	11.207%	$200.1059	$200.11	$200.10	$200.10
Purchase #4	$44.50	7.372%	$47.7805	$47.78	$47.80	$47.80
Purchase #5	$31.38	4.634%	$32.8341	$32.83	$32.85	$32.80
Purchase #6	$223.79	8.840%	$243.573	$243.57	$243.55	$243.60
Purchase #7	$106.91	4.350%	$111.5606	$111.56	$111.55	$111.60
7 purchase totals =	$697.42		$755.5128	$755.51	$755.50	$755.60