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	$82.78	3.811%	$85.9347	$85.93	$85.95	$85.90
Purchase #2	$207.46	7.160%	$222.3141	$222.31	$222.30	$222.30
Purchase #3	$244.67	4.488%	$255.6508	$255.65	$255.65	$255.70
Purchase #4	$227.31	6.832%	$242.8398	$242.84	$242.85	$242.80
Purchase #5	$165.77	11.117%	$184.1987	$184.20	$184.20	$184.20
Purchase #6	$171.67	9.315%	$187.6611	$187.66	$187.65	$187.70
Purchase #7	$34.57	3.753%	$35.8674	$35.87	$35.85	$35.90
7 purchase totals =	$1,134.23		$1,214.4666	$1,214.46	$1,214.45	$1,214.50