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	$218.36	6.771%	$233.1452	$233.15	$233.15	$233.10
Purchase #2	$77.61	10.278%	$85.5868	$85.59	$85.60	$85.60
Purchase #3	$158.56	4.563%	$165.7951	$165.80	$165.80	$165.80
Purchase #4	$148.47	3.792%	$154.1	$154.10	$154.10	$154.10
Purchase #5	$221.46	4.567%	$231.5741	$231.57	$231.55	$231.60
Purchase #6	$219.95	3.722%	$228.1365	$228.14	$228.15	$228.10
Purchase #7	$38.37	3.123%	$39.5683	$39.57	$39.55	$39.60
7 purchase totals =	$1,082.78		$1,137.9060	$1,137.92	$1,137.90	$1,137.90