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	$149.88	7.667%	$161.3713	$161.37	$161.35	$161.40
Purchase #2	$126.78	10.217%	$139.7331	$139.73	$139.75	$139.70
Purchase #3	$92.43	8.833%	$100.5943	$100.59	$100.60	$100.60
Purchase #4	$199.64	11.664%	$222.926	$222.93	$222.95	$222.90
Purchase #5	$57.39	10.584%	$63.4642	$63.46	$63.45	$63.50
Purchase #6	$149.68	4.128%	$155.8588	$155.86	$155.85	$155.90
Purchase #7	$174.83	10.612%	$193.383	$193.38	$193.40	$193.40
7 purchase totals =	$950.63		$1,037.3307	$1,037.32	$1,037.35	$1,037.40