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	$117.85	8.582%	$127.9639	$127.96	$127.95	$128.00
Purchase #2	$95.85	5.263%	$100.8946	$100.89	$100.90	$100.90
Purchase #3	$17.66	6.320%	$18.7761	$18.78	$18.80	$18.80
Purchase #4	$247.97	6.178%	$263.2896	$263.29	$263.30	$263.30
Purchase #5	$179.50	6.638%	$191.4152	$191.42	$191.40	$191.40
Purchase #6	$58.86	7.690%	$63.3863	$63.39	$63.40	$63.40
Purchase #7	$14.55	7.408%	$15.6279	$15.63	$15.65	$15.60
7 purchase totals =	$732.24		$781.3536	$781.36	$781.40	$781.40