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	$206.37	5.182%	$217.0641	$217.06	$217.05	$217.10
Purchase #2	$14.42	7.438%	$15.4926	$15.49	$15.50	$15.50
Purchase #3	$76.79	11.132%	$85.3383	$85.34	$85.35	$85.30
Purchase #4	$111.89	6.766%	$119.4605	$119.46	$119.45	$119.50
Purchase #5	$224.60	8.460%	$243.6012	$243.60	$243.60	$243.60
Purchase #6	$80.83	7.371%	$86.788	$86.79	$86.80	$86.80
Purchase #7	$126.34	12.856%	$142.5823	$142.58	$142.60	$142.60
7 purchase totals =	$841.24		$910.3270	$910.32	$910.35	$910.40