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	$88.61	7.176%	$94.9687	$94.97	$94.95	$95.00
Purchase #2	$15.27	8.666%	$16.5933	$16.59	$16.60	$16.60
Purchase #3	$89.77	10.820%	$99.4831	$99.48	$99.50	$99.50
Purchase #4	$174.94	13.382%	$198.3505	$198.35	$198.35	$198.40
Purchase #5	$109.72	3.303%	$113.3441	$113.34	$113.35	$113.30
Purchase #6	$138.47	4.163%	$144.2345	$144.23	$144.25	$144.20
Purchase #7	$81.97	9.152%	$89.4719	$89.47	$89.45	$89.50
7 purchase totals =	$698.75		$756.4461	$756.43	$756.45	$756.50