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	$228.60	7.330%	$245.3564	$245.36	$245.35	$245.40
Purchase #2	$74.52	8.422%	$80.7961	$80.80	$80.80	$80.80
Purchase #3	$128.49	10.852%	$142.4337	$142.43	$142.45	$142.40
Purchase #4	$242.67	7.757%	$261.4939	$261.49	$261.50	$261.50
Purchase #5	$241.38	3.318%	$249.389	$249.39	$249.40	$249.40
Purchase #6	$51.51	4.634%	$53.897	$53.90	$53.90	$53.90
Purchase #7	$184.45	6.392%	$196.24	$196.24	$196.25	$196.20
7 purchase totals =	$1,151.62		$1,229.6061	$1,229.61	$1,229.65	$1,229.60