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	$195.34	9.481%	$213.8602	$213.86	$213.85	$213.90
Purchase #2	$32.92	5.800%	$34.8294	$34.83	$34.85	$34.80
Purchase #3	$164.78	8.118%	$178.1568	$178.16	$178.15	$178.20
Purchase #4	$225.95	13.709%	$256.9255	$256.93	$256.95	$256.90
Purchase #5	$203.78	12.829%	$229.9229	$229.92	$229.90	$229.90
Purchase #6	$64.49	10.342%	$71.1596	$71.16	$71.15	$71.20
Purchase #7	$74.70	5.298%	$78.6576	$78.66	$78.65	$78.70
7 purchase totals =	$961.96		$1,063.5120	$1,063.52	$1,063.50	$1,063.60