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	$12.95	9.329%	$14.1581	$14.16	$14.15	$14.20
Purchase #2	$39.79	10.290%	$43.8844	$43.88	$43.90	$43.90
Purchase #3	$148.39	3.409%	$153.4486	$153.45	$153.45	$153.40
Purchase #4	$150.85	4.595%	$157.7816	$157.78	$157.80	$157.80
Purchase #5	$59.61	9.687%	$65.3844	$65.38	$65.40	$65.40
Purchase #6	$42.75	6.363%	$45.4702	$45.47	$45.45	$45.50
Purchase #7	$83.70	12.499%	$94.1617	$94.16	$94.15	$94.20
7 purchase totals =	$538.04		$574.2890	$574.28	$574.30	$574.40