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	$217.64	7.733%	$234.4701	$234.47	$234.45	$234.50
Purchase #2	$111.80	5.716%	$118.1905	$118.19	$118.20	$118.20
Purchase #3	$61.54	5.692%	$65.0429	$65.04	$65.05	$65.00
Purchase #4	$55.81	10.762%	$61.8163	$61.82	$61.80	$61.80
Purchase #5	$229.61	13.834%	$261.3742	$261.37	$261.35	$261.40
Purchase #6	$127.80	7.285%	$137.1102	$137.11	$137.10	$137.10
Purchase #7	$154.39	9.600%	$169.2114	$169.21	$169.20	$169.20
7 purchase totals =	$958.59		$1,047.2156	$1,047.21	$1,047.15	$1,047.20