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	$105.84	9.555%	$115.953	$115.95	$115.95	$116.00
Purchase #2	$169.98	5.292%	$178.9753	$178.98	$179.00	$179.00
Purchase #3	$83.46	6.695%	$89.0476	$89.05	$89.05	$89.00
Purchase #4	$99.84	9.433%	$109.2579	$109.26	$109.25	$109.30
Purchase #5	$237.85	8.243%	$257.456	$257.46	$257.45	$257.50
Purchase #6	$41.89	13.273%	$47.4501	$47.45	$47.45	$47.50
Purchase #7	$153.96	9.675%	$168.8556	$168.86	$168.85	$168.90
7 purchase totals =	$892.82		$966.9955	$967.01	$967.00	$967.20