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	$160.70	9.743%	$176.357	$176.36	$176.35	$176.40
Purchase #2	$238.43	11.444%	$265.7159	$265.72	$265.70	$265.70
Purchase #3	$92.81	8.161%	$100.3842	$100.38	$100.40	$100.40
Purchase #4	$135.31	5.599%	$142.886	$142.89	$142.90	$142.90
Purchase #5	$174.39	4.528%	$182.2864	$182.29	$182.30	$182.30
Purchase #6	$116.70	6.566%	$124.3625	$124.36	$124.35	$124.40
Purchase #7	$23.36	6.634%	$24.9097	$24.91	$24.90	$24.90
7 purchase totals =	$941.70		$1,016.9017	$1,016.91	$1,016.90	$1,017.00