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	$102.81	4.753%	$107.6966	$107.70	$107.70	$107.70
Purchase #2	$120.83	11.215%	$134.3811	$134.38	$134.40	$134.40
Purchase #3	$27.47	7.209%	$29.4503	$29.45	$29.45	$29.50
Purchase #4	$239.64	6.588%	$255.4275	$255.43	$255.45	$255.40
Purchase #5	$240.78	5.589%	$254.2372	$254.24	$254.25	$254.20
Purchase #6	$11.41	8.480%	$12.3776	$12.38	$12.40	$12.40
Purchase #7	$248.51	7.615%	$267.434	$267.43	$267.45	$267.40
7 purchase totals =	$991.45		$1,061.0043	$1,061.01	$1,061.10	$1,061.00