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	$216.58	7.849%	$233.5794	$233.58	$233.60	$233.60
Purchase #2	$45.48	11.208%	$50.5774	$50.58	$50.60	$50.60
Purchase #3	$227.86	11.682%	$254.4786	$254.48	$254.50	$254.50
Purchase #4	$186.32	5.783%	$197.0949	$197.09	$197.10	$197.10
Purchase #5	$33.38	7.682%	$35.9443	$35.94	$35.95	$35.90
Purchase #6	$181.51	8.295%	$196.5663	$196.57	$196.55	$196.60
Purchase #7	$102.89	4.672%	$107.697	$107.70	$107.70	$107.70
7 purchase totals =	$994.02		$1,075.9379	$1,075.94	$1,076.00	$1,076.00