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	$213.88	3.558%	$221.4899	$221.49	$221.50	$221.50
Purchase #2	$172.55	10.137%	$190.0414	$190.04	$190.05	$190.00
Purchase #3	$186.58	5.102%	$196.0993	$196.10	$196.10	$196.10
Purchase #4	$106.91	6.766%	$114.1435	$114.14	$114.15	$114.10
Purchase #5	$86.93	8.655%	$94.4538	$94.45	$94.45	$94.50
Purchase #6	$165.43	4.600%	$173.0398	$173.04	$173.05	$173.00
Purchase #7	$162.60	9.769%	$178.4844	$178.48	$178.50	$178.50
7 purchase totals =	$1,094.88		$1,167.7521	$1,167.74	$1,167.80	$1,167.70