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	$84.28	13.342%	$95.5246	$95.52	$95.50	$95.50
Purchase #2	$91.28	4.653%	$95.5273	$95.53	$95.55	$95.50
Purchase #3	$234.50	12.762%	$264.4269	$264.43	$264.45	$264.40
Purchase #4	$30.27	8.295%	$32.7809	$32.78	$32.80	$32.80
Purchase #5	$167.68	10.566%	$185.3971	$185.40	$185.40	$185.40
Purchase #6	$195.84	11.362%	$218.0913	$218.09	$218.10	$218.10
Purchase #7	$71.65	4.501%	$74.875	$74.88	$74.90	$74.90
7 purchase totals =	$875.50		$966.6231	$966.63	$966.70	$966.60