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	$196.64	11.802%	$219.8475	$219.85	$219.85	$219.80
Purchase #2	$124.56	11.669%	$139.0949	$139.09	$139.10	$139.10
Purchase #3	$170.66	9.153%	$186.2805	$186.28	$186.30	$186.30
Purchase #4	$85.94	11.687%	$95.9838	$95.98	$96.00	$96.00
Purchase #5	$160.96	3.444%	$166.5035	$166.50	$166.50	$166.50
Purchase #6	$95.56	4.535%	$99.8936	$99.89	$99.90	$99.90
Purchase #7	$42.96	5.180%	$45.1853	$45.19	$45.20	$45.20
7 purchase totals =	$877.28		$952.7891	$952.78	$952.85	$952.80