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	$60.70	11.786%	$67.8541	$67.85	$67.85	$67.90
Purchase #2	$218.82	5.603%	$231.0805	$231.08	$231.10	$231.10
Purchase #3	$131.51	9.250%	$143.6747	$143.67	$143.65	$143.70
Purchase #4	$41.26	12.729%	$46.512	$46.51	$46.50	$46.50
Purchase #5	$80.93	6.133%	$85.8934	$85.89	$85.90	$85.90
Purchase #6	$155.27	4.314%	$161.9683	$161.97	$161.95	$162.00
Purchase #7	$242.95	12.683%	$273.7633	$273.76	$273.75	$273.80
7 purchase totals =	$931.44		$1,010.7463	$1,010.73	$1,010.70	$1,010.90