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	$127.34	3.570%	$131.886	$131.89	$131.90	$131.90
Purchase #2	$18.42	9.609%	$20.19	$20.19	$20.20	$20.20
Purchase #3	$95.55	10.236%	$105.3305	$105.33	$105.35	$105.30
Purchase #4	$38.77	13.520%	$44.0117	$44.01	$44.00	$44.00
Purchase #5	$138.84	5.253%	$146.1333	$146.13	$146.15	$146.10
Purchase #6	$221.52	8.287%	$239.8774	$239.88	$239.90	$239.90
Purchase #7	$41.47	8.781%	$45.1115	$45.11	$45.10	$45.10
7 purchase totals =	$681.91		$732.5404	$732.54	$732.60	$732.50