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	$132.63	9.372%	$145.0601	$145.06	$145.05	$145.10
Purchase #2	$89.98	5.291%	$94.7408	$94.74	$94.75	$94.70
Purchase #3	$198.80	8.114%	$214.9306	$214.93	$214.95	$214.90
Purchase #4	$231.45	13.683%	$263.1193	$263.12	$263.10	$263.10
Purchase #5	$62.54	13.334%	$70.8791	$70.88	$70.90	$70.90
Purchase #6	$246.72	3.723%	$255.9054	$255.91	$255.90	$255.90
Purchase #7	$21.77	12.613%	$24.5159	$24.52	$24.50	$24.50
7 purchase totals =	$983.89		$1,069.1512	$1,069.16	$1,069.15	$1,069.10