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	$243.32	4.285%	$253.7463	$253.75	$253.75	$253.70
Purchase #2	$74.77	9.470%	$81.8507	$81.85	$81.85	$81.90
Purchase #3	$77.87	6.208%	$82.7042	$82.70	$82.70	$82.70
Purchase #4	$194.43	12.868%	$219.4493	$219.45	$219.45	$219.40
Purchase #5	$210.59	5.874%	$222.9601	$222.96	$222.95	$223.00
Purchase #6	$77.66	12.330%	$87.2355	$87.24	$87.25	$87.20
Purchase #7	$84.28	6.256%	$89.5526	$89.55	$89.55	$89.60
7 purchase totals =	$962.92		$1,037.4987	$1,037.50	$1,037.50	$1,037.50