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	$97.93	8.164%	$105.925	$105.93	$105.95	$105.90
Purchase #2	$36.27	3.691%	$37.6087	$37.61	$37.60	$37.60
Purchase #3	$47.85	8.388%	$51.8637	$51.86	$51.85	$51.90
Purchase #4	$114.35	10.827%	$126.7307	$126.73	$126.75	$126.70
Purchase #5	$38.78	10.716%	$42.9357	$42.94	$42.95	$42.90
Purchase #6	$115.94	3.361%	$119.8367	$119.84	$119.85	$119.80
Purchase #7	$70.76	13.438%	$80.2687	$80.27	$80.25	$80.30
7 purchase totals =	$521.88		$565.1692	$565.18	$565.20	$565.10