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	$62.82	10.528%	$69.4337	$69.43	$69.45	$69.40
Purchase #2	$134.78	7.382%	$144.7295	$144.73	$144.75	$144.70
Purchase #3	$125.87	5.438%	$132.7148	$132.71	$132.70	$132.70
Purchase #4	$236.47	8.561%	$256.7142	$256.71	$256.70	$256.70
Purchase #5	$231.60	11.612%	$258.4934	$258.49	$258.50	$258.50
Purchase #6	$73.67	12.621%	$82.9679	$82.97	$82.95	$83.00
Purchase #7	$83.44	7.771%	$89.9241	$89.92	$89.90	$89.90
7 purchase totals =	$948.65		$1,034.9776	$1,034.96	$1,034.95	$1,034.90