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	$107.33	4.476%	$112.1341	$112.13	$112.15	$112.10
Purchase #2	$13.25	9.166%	$14.4645	$14.46	$14.45	$14.50
Purchase #3	$75.89	8.103%	$82.0394	$82.04	$82.05	$82.00
Purchase #4	$163.33	5.860%	$172.9011	$172.90	$172.90	$172.90
Purchase #5	$94.75	10.571%	$104.766	$104.77	$104.75	$104.80
Purchase #6	$95.82	8.833%	$104.2838	$104.28	$104.30	$104.30
Purchase #7	$108.36	13.368%	$122.8456	$122.85	$122.85	$122.80
7 purchase totals =	$658.73		$713.4345	$713.43	$713.45	$713.40