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	$40.25	9.141%	$43.9293	$43.93	$43.95	$43.90
Purchase #2	$23.39	10.552%	$25.8581	$25.86	$25.85	$25.90
Purchase #3	$37.89	4.296%	$39.5178	$39.52	$39.50	$39.50
Purchase #4	$199.46	4.169%	$207.7755	$207.78	$207.80	$207.80
Purchase #5	$131.73	6.196%	$139.892	$139.89	$139.90	$139.90
Purchase #6	$173.77	3.147%	$179.2385	$179.24	$179.25	$179.20
Purchase #7	$92.58	8.560%	$100.5048	$100.50	$100.50	$100.50
7 purchase totals =	$699.07		$736.7160	$736.72	$736.75	$736.70