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	$148.64	11.402%	$165.5879	$165.59	$165.60	$165.60
Purchase #2	$100.37	9.867%	$110.2735	$110.27	$110.25	$110.30
Purchase #3	$34.82	9.509%	$38.131	$38.13	$38.15	$38.10
Purchase #4	$135.47	9.372%	$148.1662	$148.17	$148.15	$148.20
Purchase #5	$177.28	13.346%	$200.9398	$200.94	$200.95	$200.90
Purchase #6	$142.78	7.361%	$153.29	$153.29	$153.30	$153.30
Purchase #7	$229.53	3.456%	$237.4626	$237.46	$237.45	$237.50
7 purchase totals =	$968.89		$1,053.8510	$1,053.85	$1,053.85	$1,053.90