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	$214.84	3.348%	$222.0328	$222.03	$222.05	$222.00
Purchase #2	$78.51	11.335%	$87.4091	$87.41	$87.40	$87.40
Purchase #3	$204.37	10.472%	$225.7716	$225.77	$225.75	$225.80
Purchase #4	$12.66	11.427%	$14.1067	$14.11	$14.10	$14.10
Purchase #5	$226.38	7.151%	$242.5684	$242.57	$242.55	$242.60
Purchase #6	$232.35	9.151%	$253.6123	$253.61	$253.60	$253.60
Purchase #7	$35.58	12.716%	$40.1044	$40.10	$40.10	$40.10
7 purchase totals =	$1,004.69		$1,085.6053	$1,085.60	$1,085.55	$1,085.60