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	$196.61	5.833%	$208.0783	$208.08	$208.10	$208.10
Purchase #2	$242.50	6.436%	$258.1073	$258.11	$258.10	$258.10
Purchase #3	$72.77	7.118%	$77.9498	$77.95	$77.95	$77.90
Purchase #4	$72.46	12.110%	$81.2349	$81.23	$81.25	$81.20
Purchase #5	$59.46	5.531%	$62.7487	$62.75	$62.75	$62.70
Purchase #6	$90.95	4.467%	$95.0127	$95.01	$95.00	$95.00
Purchase #7	$231.63	10.864%	$256.7943	$256.79	$256.80	$256.80
7 purchase totals =	$966.38		$1,039.9260	$1,039.92	$1,039.95	$1,039.80