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	$178.70	9.488%	$195.6551	$195.66	$195.65	$195.70
Purchase #2	$161.85	3.240%	$167.0939	$167.09	$167.10	$167.10
Purchase #3	$95.91	13.388%	$108.7504	$108.75	$108.75	$108.80
Purchase #4	$199.61	11.141%	$221.8486	$221.85	$221.85	$221.80
Purchase #5	$98.52	5.427%	$103.8667	$103.87	$103.85	$103.90
Purchase #6	$167.70	11.405%	$186.8262	$186.83	$186.85	$186.80
Purchase #7	$79.43	7.723%	$85.5644	$85.56	$85.55	$85.60
7 purchase totals =	$981.72		$1,069.6053	$1,069.61	$1,069.60	$1,069.70