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	$86.68	10.503%	$95.784	$95.78	$95.80	$95.80
Purchase #2	$6.31	4.184%	$6.574	$6.57	$6.55	$6.60
Purchase #3	$28.83	12.782%	$32.5151	$32.52	$32.50	$32.50
Purchase #4	$22.73	13.309%	$25.7551	$25.76	$25.75	$25.80
Purchase #5	$35.47	8.334%	$38.4261	$38.43	$38.45	$38.40
Purchase #6	$210.30	5.729%	$222.3481	$222.35	$222.35	$222.30
Purchase #7	$81.58	13.117%	$92.2808	$92.28	$92.30	$92.30
7 purchase totals =	$471.90		$513.6832	$513.69	$513.70	$513.70