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	$126.89	13.173%	$143.6052	$143.61	$143.60	$143.60
Purchase #2	$142.75	7.563%	$153.5462	$153.55	$153.55	$153.50
Purchase #3	$196.64	4.522%	$205.5321	$205.53	$205.55	$205.50
Purchase #4	$244.63	4.645%	$255.9931	$255.99	$256.00	$256.00
Purchase #5	$55.81	4.863%	$58.524	$58.52	$58.50	$58.50
Purchase #6	$76.80	8.448%	$83.2881	$83.29	$83.30	$83.30
Purchase #7	$148.72	9.257%	$162.487	$162.49	$162.50	$162.50
7 purchase totals =	$992.24		$1,062.9757	$1,062.98	$1,063.00	$1,062.90