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	$213.40	4.751%	$223.5386	$223.54	$223.55	$223.50
Purchase #2	$9.86	10.397%	$10.8851	$10.89	$10.90	$10.90
Purchase #3	$65.39	13.291%	$74.081	$74.08	$74.10	$74.10
Purchase #4	$110.73	13.430%	$125.601	$125.60	$125.60	$125.60
Purchase #5	$12.46	4.690%	$13.0444	$13.04	$13.05	$13.00
Purchase #6	$93.53	9.589%	$102.4986	$102.50	$102.50	$102.50
Purchase #7	$100.69	10.771%	$111.5353	$111.54	$111.55	$111.50
7 purchase totals =	$606.06		$661.1840	$661.19	$661.25	$661.10