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	$13.85	5.410%	$14.5993	$14.60	$14.60	$14.60
Purchase #2	$30.91	6.567%	$32.9399	$32.94	$32.95	$32.90
Purchase #3	$173.65	5.781%	$183.6887	$183.69	$183.70	$183.70
Purchase #4	$206.73	8.288%	$223.8638	$223.86	$223.85	$223.90
Purchase #5	$87.83	9.153%	$95.8691	$95.87	$95.85	$95.90
Purchase #6	$118.49	11.330%	$131.9149	$131.91	$131.90	$131.90
Purchase #7	$208.52	10.579%	$230.5793	$230.58	$230.60	$230.60
7 purchase totals =	$839.98		$913.4550	$913.45	$913.45	$913.50