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	$105.39	8.388%	$114.2301	$114.23	$114.25	$114.20
Purchase #2	$15.71	11.223%	$17.4731	$17.47	$17.45	$17.50
Purchase #3	$37.91	12.345%	$42.59	$42.59	$42.60	$42.60
Purchase #4	$95.77	8.270%	$103.6902	$103.69	$103.70	$103.70
Purchase #5	$117.44	9.461%	$128.551	$128.55	$128.55	$128.60
Purchase #6	$101.91	12.741%	$114.8944	$114.89	$114.90	$114.90
Purchase #7	$143.94	13.604%	$163.5216	$163.52	$163.50	$163.50
7 purchase totals =	$618.07		$684.9504	$684.94	$684.95	$685.00