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	$59.35	7.334%	$63.7027	$63.70	$63.70	$63.70
Purchase #2	$80.72	6.174%	$85.7037	$85.70	$85.70	$85.70
Purchase #3	$53.79	11.352%	$59.8962	$59.90	$59.90	$59.90
Purchase #4	$146.30	8.584%	$158.8584	$158.86	$158.85	$158.90
Purchase #5	$89.78	6.806%	$95.8904	$95.89	$95.90	$95.90
Purchase #6	$178.60	11.318%	$198.8139	$198.81	$198.80	$198.80
Purchase #7	$91.40	4.253%	$95.2872	$95.29	$95.30	$95.30
7 purchase totals =	$699.94		$758.1525	$758.15	$758.15	$758.20