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	$60.86	4.738%	$63.7435	$63.74	$63.75	$63.70
Purchase #2	$17.28	12.654%	$19.4666	$19.47	$19.45	$19.50
Purchase #3	$234.70	12.588%	$264.244	$264.24	$264.25	$264.20
Purchase #4	$53.31	11.319%	$59.3442	$59.34	$59.35	$59.30
Purchase #5	$110.53	5.193%	$116.2698	$116.27	$116.25	$116.30
Purchase #6	$46.59	11.613%	$52.0005	$52.00	$52.00	$52.00
Purchase #7	$138.52	8.672%	$150.5325	$150.53	$150.55	$150.50
7 purchase totals =	$661.79		$725.6011	$725.59	$725.60	$725.50