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	$60.47	11.847%	$67.6339	$67.63	$67.65	$67.60
Purchase #2	$187.95	13.610%	$213.53	$213.53	$213.55	$213.50
Purchase #3	$148.63	9.524%	$162.7855	$162.79	$162.80	$162.80
Purchase #4	$118.64	8.611%	$128.8561	$128.86	$128.85	$128.90
Purchase #5	$165.48	11.848%	$185.0861	$185.09	$185.10	$185.10
Purchase #6	$217.71	12.339%	$244.5732	$244.57	$244.55	$244.60
Purchase #7	$30.46	6.593%	$32.4682	$32.47	$32.45	$32.50
7 purchase totals =	$929.34		$1,034.9330	$1,034.94	$1,034.95	$1,035.00