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	$196.98	7.757%	$212.2597	$212.26	$212.25	$212.30
Purchase #2	$137.65	9.614%	$150.8837	$150.88	$150.90	$150.90
Purchase #3	$65.79	8.166%	$71.1624	$71.16	$71.15	$71.20
Purchase #4	$157.34	7.247%	$168.7424	$168.74	$168.75	$168.70
Purchase #5	$13.64	7.164%	$14.6172	$14.62	$14.60	$14.60
Purchase #6	$30.80	5.577%	$32.5177	$32.52	$32.50	$32.50
Purchase #7	$136.39	11.376%	$151.9057	$151.91	$151.90	$151.90
7 purchase totals =	$738.59		$802.0888	$802.09	$802.05	$802.10