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	$85.76	10.524%	$94.7854	$94.79	$94.80	$94.80
Purchase #2	$181.31	8.493%	$196.7087	$196.71	$196.70	$196.70
Purchase #3	$100.84	7.848%	$108.7539	$108.75	$108.75	$108.80
Purchase #4	$208.31	11.171%	$231.5803	$231.58	$231.60	$231.60
Purchase #5	$176.78	8.379%	$191.5924	$191.59	$191.60	$191.60
Purchase #6	$14.68	4.832%	$15.3893	$15.39	$15.40	$15.40
Purchase #7	$186.87	11.528%	$208.4124	$208.41	$208.40	$208.40
7 purchase totals =	$954.55		$1,047.2224	$1,047.22	$1,047.25	$1,047.30