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	$58.81	11.398%	$65.5132	$65.51	$65.50	$65.50
Purchase #2	$90.53	4.242%	$94.3703	$94.37	$94.35	$94.40
Purchase #3	$80.99	3.792%	$84.0611	$84.06	$84.05	$84.10
Purchase #4	$134.57	5.358%	$141.7803	$141.78	$141.80	$141.80
Purchase #5	$230.60	7.803%	$248.5937	$248.59	$248.60	$248.60
Purchase #6	$208.45	11.861%	$233.1743	$233.17	$233.15	$233.20
Purchase #7	$134.68	12.770%	$151.8786	$151.88	$151.90	$151.90
7 purchase totals =	$938.63		$1,019.3715	$1,019.36	$1,019.35	$1,019.50