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	$224.89	3.858%	$233.5663	$233.57	$233.55	$233.60
Purchase #2	$38.82	4.773%	$40.6729	$40.67	$40.65	$40.70
Purchase #3	$11.69	12.728%	$13.1779	$13.18	$13.20	$13.20
Purchase #4	$62.58	5.482%	$66.0106	$66.01	$66.00	$66.00
Purchase #5	$167.79	13.366%	$190.2168	$190.22	$190.20	$190.20
Purchase #6	$211.48	6.511%	$225.2495	$225.25	$225.25	$225.20
Purchase #7	$236.84	8.337%	$256.5854	$256.59	$256.60	$256.60
7 purchase totals =	$954.09		$1,025.4794	$1,025.49	$1,025.45	$1,025.50