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	$119.48	10.619%	$132.1676	$132.17	$132.15	$132.20
Purchase #2	$91.75	12.651%	$103.3573	$103.36	$103.35	$103.40
Purchase #3	$136.95	11.445%	$152.6239	$152.62	$152.60	$152.60
Purchase #4	$205.75	9.822%	$225.9588	$225.96	$225.95	$226.00
Purchase #5	$126.51	10.354%	$139.6088	$139.61	$139.60	$139.60
Purchase #6	$241.90	6.336%	$257.2268	$257.23	$257.25	$257.20
Purchase #7	$103.69	7.598%	$111.5684	$111.57	$111.55	$111.60
7 purchase totals =	$1,026.03		$1,122.5116	$1,122.52	$1,122.45	$1,122.60