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	$159.77	9.436%	$174.8459	$174.85	$174.85	$174.80
Purchase #2	$37.41	13.341%	$42.4009	$42.40	$42.40	$42.40
Purchase #3	$200.81	6.155%	$213.1699	$213.17	$213.15	$213.20
Purchase #4	$9.52	13.770%	$10.8309	$10.83	$10.85	$10.80
Purchase #5	$94.40	4.243%	$98.4054	$98.41	$98.40	$98.40
Purchase #6	$229.37	7.509%	$246.5934	$246.59	$246.60	$246.60
Purchase #7	$218.25	9.600%	$239.202	$239.20	$239.20	$239.20
7 purchase totals =	$949.53		$1,025.4484	$1,025.45	$1,025.45	$1,025.40