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	$196.27	9.397%	$214.7135	$214.71	$214.70	$214.70
Purchase #2	$139.96	9.198%	$152.8335	$152.83	$152.85	$152.80
Purchase #3	$47.75	13.276%	$54.0893	$54.09	$54.10	$54.10
Purchase #4	$235.46	11.275%	$262.0081	$262.01	$262.00	$262.00
Purchase #5	$33.71	4.106%	$35.0941	$35.09	$35.10	$35.10
Purchase #6	$217.58	13.459%	$246.8641	$246.86	$246.85	$246.90
Purchase #7	$76.33	8.495%	$82.8142	$82.81	$82.80	$82.80
7 purchase totals =	$947.06		$1,048.4168	$1,048.40	$1,048.40	$1,048.40