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	$247.34	10.793%	$274.0354	$274.04	$274.05	$274.00
Purchase #2	$10.34	10.149%	$11.3894	$11.39	$11.40	$11.40
Purchase #3	$151.48	10.836%	$167.8944	$167.89	$167.90	$167.90
Purchase #4	$145.41	13.189%	$164.5881	$164.59	$164.60	$164.60
Purchase #5	$191.69	4.477%	$200.272	$200.27	$200.25	$200.30
Purchase #6	$27.99	3.337%	$28.924	$28.92	$28.90	$28.90
Purchase #7	$177.93	11.186%	$197.8332	$197.83	$197.85	$197.80
7 purchase totals =	$952.18		$1,044.9365	$1,044.93	$1,044.95	$1,044.90