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	$190.48	9.813%	$209.1718	$209.17	$209.15	$209.20
Purchase #2	$53.73	11.104%	$59.6962	$59.70	$59.70	$59.70
Purchase #3	$215.82	4.453%	$225.4305	$225.43	$225.45	$225.40
Purchase #4	$163.43	5.468%	$172.3664	$172.37	$172.35	$172.40
Purchase #5	$228.48	10.558%	$252.6029	$252.60	$252.60	$252.60
Purchase #6	$99.32	7.255%	$106.5257	$106.53	$106.55	$106.50
Purchase #7	$85.57	4.155%	$89.1254	$89.13	$89.15	$89.10
7 purchase totals =	$1,036.83		$1,114.9189	$1,114.93	$1,114.95	$1,114.90