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	$191.38	11.857%	$214.0719	$214.07	$214.05	$214.10
Purchase #2	$38.79	6.163%	$41.1806	$41.18	$41.20	$41.20
Purchase #3	$210.62	5.688%	$222.6001	$222.60	$222.60	$222.60
Purchase #4	$69.76	10.720%	$77.2383	$77.24	$77.25	$77.20
Purchase #5	$50.53	3.240%	$52.1672	$52.17	$52.15	$52.20
Purchase #6	$94.53	6.619%	$100.7869	$100.79	$100.80	$100.80
Purchase #7	$229.90	11.721%	$256.8466	$256.85	$256.85	$256.80
7 purchase totals =	$885.51		$964.8916	$964.90	$964.90	$964.90