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	$174.87	11.349%	$194.716	$194.72	$194.70	$194.70
Purchase #2	$27.53	13.182%	$31.159	$31.16	$31.15	$31.20
Purchase #3	$189.72	10.471%	$209.5856	$209.59	$209.60	$209.60
Purchase #4	$104.45	7.466%	$112.2482	$112.25	$112.25	$112.20
Purchase #5	$157.31	9.592%	$172.3992	$172.40	$172.40	$172.40
Purchase #6	$235.56	3.316%	$243.3712	$243.37	$243.35	$243.40
Purchase #7	$125.49	5.753%	$132.7094	$132.71	$132.70	$132.70
7 purchase totals =	$1,014.93		$1,096.1886	$1,096.20	$1,096.15	$1,096.20