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	$192.36	4.422%	$200.8662	$200.87	$200.85	$200.90
Purchase #2	$79.94	8.180%	$86.4791	$86.48	$86.50	$86.50
Purchase #3	$92.78	3.352%	$95.89	$95.89	$95.90	$95.90
Purchase #4	$74.86	11.529%	$83.4906	$83.49	$83.50	$83.50
Purchase #5	$173.57	3.405%	$179.4801	$179.48	$179.50	$179.50
Purchase #6	$68.80	6.483%	$73.2603	$73.26	$73.25	$73.30
Purchase #7	$50.73	10.421%	$56.0166	$56.02	$56.00	$56.00
7 purchase totals =	$733.04		$775.4829	$775.49	$775.50	$775.60