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	$94.35	7.490%	$101.4168	$101.42	$101.40	$101.40
Purchase #2	$12.31	4.772%	$12.8974	$12.90	$12.90	$12.90
Purchase #3	$136.51	3.870%	$141.7929	$141.79	$141.80	$141.80
Purchase #4	$230.25	5.515%	$242.9483	$242.95	$242.95	$242.90
Purchase #5	$175.29	12.353%	$196.9436	$196.94	$196.95	$196.90
Purchase #6	$199.58	9.487%	$218.5142	$218.51	$218.50	$218.50
Purchase #7	$87.67	13.414%	$99.4301	$99.43	$99.45	$99.40
7 purchase totals =	$935.96		$1,013.9433	$1,013.94	$1,013.95	$1,013.80