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	$78.74	11.271%	$87.6148	$87.61	$87.60	$87.60
Purchase #2	$70.63	8.538%	$76.6604	$76.66	$76.65	$76.70
Purchase #3	$43.80	4.806%	$45.905	$45.91	$45.90	$45.90
Purchase #4	$194.34	8.291%	$210.4527	$210.45	$210.45	$210.50
Purchase #5	$142.69	11.357%	$158.8953	$158.90	$158.90	$158.90
Purchase #6	$168.38	13.379%	$190.9076	$190.91	$190.90	$190.90
Purchase #7	$249.69	11.403%	$278.1622	$278.16	$278.15	$278.20
7 purchase totals =	$948.27		$1,048.5980	$1,048.60	$1,048.55	$1,048.70