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	$228.81	4.350%	$238.7632	$238.76	$238.75	$238.80
Purchase #2	$38.42	4.465%	$40.1355	$40.14	$40.15	$40.10
Purchase #3	$205.57	5.683%	$217.2525	$217.25	$217.25	$217.30
Purchase #4	$100.35	3.186%	$103.5472	$103.55	$103.55	$103.50
Purchase #5	$191.75	3.573%	$198.6012	$198.60	$198.60	$198.60
Purchase #6	$17.88	4.396%	$18.666	$18.67	$18.65	$18.70
Purchase #7	$241.95	10.327%	$266.9362	$266.94	$266.95	$266.90
7 purchase totals =	$1,024.73		$1,083.9018	$1,083.91	$1,083.90	$1,083.90