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	$82.92	3.714%	$85.9996	$86.00	$86.00	$86.00
Purchase #2	$34.86	11.189%	$38.7605	$38.76	$38.75	$38.80
Purchase #3	$75.61	12.839%	$85.3176	$85.32	$85.30	$85.30
Purchase #4	$173.29	13.519%	$196.7171	$196.72	$196.70	$196.70
Purchase #5	$134.30	6.297%	$142.7569	$142.76	$142.75	$142.80
Purchase #6	$226.95	8.177%	$245.5077	$245.51	$245.50	$245.50
Purchase #7	$241.47	13.770%	$274.7204	$274.72	$274.70	$274.70
7 purchase totals =	$969.40		$1,069.7798	$1,069.79	$1,069.70	$1,069.80