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	$151.86	8.313%	$164.4841	$164.48	$164.50	$164.50
Purchase #2	$30.26	3.236%	$31.2392	$31.24	$31.25	$31.20
Purchase #3	$233.60	3.592%	$241.9909	$241.99	$242.00	$242.00
Purchase #4	$211.78	9.144%	$231.1452	$231.15	$231.15	$231.10
Purchase #5	$35.45	13.309%	$40.168	$40.17	$40.15	$40.20
Purchase #6	$217.89	3.390%	$225.2765	$225.28	$225.30	$225.30
Purchase #7	$95.64	5.275%	$100.685	$100.69	$100.70	$100.70
7 purchase totals =	$976.48		$1,034.9889	$1,035.00	$1,035.05	$1,035.00