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	$207.90	4.783%	$217.8439	$217.84	$217.85	$217.80
Purchase #2	$169.79	10.258%	$187.2071	$187.21	$187.20	$187.20
Purchase #3	$95.67	10.685%	$105.8923	$105.89	$105.90	$105.90
Purchase #4	$102.90	8.751%	$111.9048	$111.90	$111.90	$111.90
Purchase #5	$68.92	9.442%	$75.4274	$75.43	$75.45	$75.40
Purchase #6	$107.92	3.732%	$111.9476	$111.95	$111.95	$111.90
Purchase #7	$111.61	12.503%	$125.5646	$125.56	$125.55	$125.60
7 purchase totals =	$864.71		$935.7877	$935.78	$935.80	$935.70