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	$98.49	13.574%	$111.859	$111.86	$111.85	$111.90
Purchase #2	$184.40	8.504%	$200.0814	$200.08	$200.10	$200.10
Purchase #3	$46.43	3.277%	$47.9515	$47.95	$47.95	$48.00
Purchase #4	$56.32	3.752%	$58.4331	$58.43	$58.45	$58.40
Purchase #5	$166.26	9.157%	$181.4844	$181.48	$181.50	$181.50
Purchase #6	$72.34	6.272%	$76.8772	$76.88	$76.90	$76.90
Purchase #7	$244.44	4.746%	$256.0411	$256.04	$256.05	$256.00
7 purchase totals =	$868.68		$932.7277	$932.72	$932.80	$932.80