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	$80.57	6.677%	$85.9497	$85.95	$85.95	$85.90
Purchase #2	$87.74	8.256%	$94.9838	$94.98	$95.00	$95.00
Purchase #3	$89.48	6.557%	$95.3472	$95.35	$95.35	$95.30
Purchase #4	$166.59	9.449%	$182.3311	$182.33	$182.35	$182.30
Purchase #5	$100.73	6.234%	$107.0095	$107.01	$107.00	$107.00
Purchase #6	$69.47	11.582%	$77.516	$77.52	$77.50	$77.50
Purchase #7	$94.83	11.484%	$105.7203	$105.72	$105.70	$105.70
7 purchase totals =	$689.41		$748.8576	$748.86	$748.85	$748.70