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	$219.86	10.395%	$242.7144	$242.71	$242.70	$242.70
Purchase #2	$64.79	6.413%	$68.945	$68.95	$68.95	$68.90
Purchase #3	$95.47	4.646%	$99.9055	$99.91	$99.90	$99.90
Purchase #4	$195.69	7.560%	$210.4842	$210.48	$210.50	$210.50
Purchase #5	$179.84	11.150%	$199.8922	$199.89	$199.90	$199.90
Purchase #6	$113.83	11.445%	$126.8578	$126.86	$126.85	$126.90
Purchase #7	$174.29	12.332%	$195.7834	$195.78	$195.80	$195.80
7 purchase totals =	$1,043.77		$1,144.5825	$1,144.58	$1,144.60	$1,144.60