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	$226.82	4.439%	$236.8885	$236.89	$236.90	$236.90
Purchase #2	$205.45	5.700%	$217.1607	$217.16	$217.15	$217.20
Purchase #3	$17.88	3.277%	$18.4659	$18.47	$18.45	$18.50
Purchase #4	$76.52	6.767%	$81.6981	$81.70	$81.70	$81.70
Purchase #5	$123.94	6.196%	$131.6193	$131.62	$131.60	$131.60
Purchase #6	$132.71	6.506%	$141.3441	$141.34	$141.35	$141.30
Purchase #7	$179.27	10.754%	$198.5487	$198.55	$198.55	$198.50
7 purchase totals =	$962.59		$1,025.7253	$1,025.73	$1,025.70	$1,025.70