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	$198.48	3.325%	$205.0795	$205.08	$205.10	$205.10
Purchase #2	$88.54	11.821%	$99.0063	$99.01	$99.00	$99.00
Purchase #3	$13.56	11.701%	$15.1467	$15.15	$15.15	$15.10
Purchase #4	$157.97	11.228%	$175.7069	$175.71	$175.70	$175.70
Purchase #5	$134.52	13.343%	$152.469	$152.47	$152.45	$152.50
Purchase #6	$238.53	10.194%	$262.8457	$262.85	$262.85	$262.80
Purchase #7	$248.59	3.601%	$257.5417	$257.54	$257.55	$257.50
7 purchase totals =	$1,080.19		$1,167.7958	$1,167.81	$1,167.80	$1,167.70