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	$102.45	8.552%	$111.2115	$111.21	$111.20	$111.20
Purchase #2	$201.54	6.674%	$214.9908	$214.99	$215.00	$215.00
Purchase #3	$62.98	5.476%	$66.4288	$66.43	$66.45	$66.40
Purchase #4	$128.31	10.403%	$141.6581	$141.66	$141.65	$141.70
Purchase #5	$176.77	11.287%	$196.722	$196.72	$196.70	$196.70
Purchase #6	$193.93	11.135%	$215.5241	$215.52	$215.50	$215.50
Purchase #7	$99.50	3.482%	$102.9646	$102.96	$102.95	$103.00
7 purchase totals =	$965.48		$1,049.4999	$1,049.49	$1,049.45	$1,049.50