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	$179.83	9.277%	$196.5128	$196.51	$196.50	$196.50
Purchase #2	$154.26	9.485%	$168.8916	$168.89	$168.90	$168.90
Purchase #3	$18.25	8.495%	$19.8003	$19.80	$19.80	$19.80
Purchase #4	$43.56	11.342%	$48.5006	$48.50	$48.50	$48.50
Purchase #5	$48.51	8.447%	$52.6076	$52.61	$52.60	$52.60
Purchase #6	$175.67	9.365%	$192.1215	$192.12	$192.10	$192.10
Purchase #7	$64.45	3.452%	$66.6748	$66.67	$66.65	$66.70
7 purchase totals =	$684.53		$745.1092	$745.10	$745.05	$745.10