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	$85.45	11.185%	$95.0076	$95.01	$95.00	$95.00
Purchase #2	$47.26	9.765%	$51.8749	$51.87	$51.85	$51.90
Purchase #3	$226.88	7.783%	$244.5381	$244.54	$244.55	$244.50
Purchase #4	$161.30	4.340%	$168.3004	$168.30	$168.30	$168.30
Purchase #5	$107.77	6.141%	$114.3882	$114.39	$114.40	$114.40
Purchase #6	$127.82	11.715%	$142.7941	$142.79	$142.80	$142.80
Purchase #7	$49.38	7.226%	$52.9482	$52.95	$52.95	$52.90
7 purchase totals =	$805.86		$869.8515	$869.85	$869.85	$869.80