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	$221.94	5.158%	$233.3877	$233.39	$233.40	$233.40
Purchase #2	$225.85	9.429%	$247.1454	$247.15	$247.15	$247.10
Purchase #3	$66.32	4.508%	$69.3097	$69.31	$69.30	$69.30
Purchase #4	$112.31	7.365%	$120.5816	$120.58	$120.60	$120.60
Purchase #5	$124.33	13.782%	$141.4652	$141.47	$141.45	$141.50
Purchase #6	$131.32	11.362%	$146.2406	$146.24	$146.25	$146.20
Purchase #7	$155.51	12.777%	$175.3795	$175.38	$175.40	$175.40
7 purchase totals =	$1,037.58		$1,133.5097	$1,133.52	$1,133.55	$1,133.50