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	$192.78	10.872%	$213.739	$213.74	$213.75	$213.70
Purchase #2	$34.57	9.698%	$37.9226	$37.92	$37.90	$37.90
Purchase #3	$137.48	9.444%	$150.4636	$150.46	$150.45	$150.50
Purchase #4	$119.60	5.361%	$126.0118	$126.01	$126.00	$126.00
Purchase #5	$176.47	5.493%	$186.1635	$186.16	$186.15	$186.20
Purchase #6	$73.60	6.273%	$78.2169	$78.22	$78.20	$78.20
Purchase #7	$127.31	10.420%	$140.5757	$140.58	$140.60	$140.60
7 purchase totals =	$861.81		$933.0931	$933.09	$933.05	$933.10