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	$119.51	12.441%	$134.3782	$134.38	$134.40	$134.40
Purchase #2	$187.62	3.864%	$194.8696	$194.87	$194.85	$194.90
Purchase #3	$148.86	7.119%	$159.4573	$159.46	$159.45	$159.50
Purchase #4	$194.46	12.146%	$218.0791	$218.08	$218.10	$218.10
Purchase #5	$134.52	3.759%	$139.5766	$139.58	$139.60	$139.60
Purchase #6	$132.94	10.214%	$146.5185	$146.52	$146.50	$146.50
Purchase #7	$114.51	3.486%	$118.5018	$118.50	$118.50	$118.50
7 purchase totals =	$1,032.42		$1,111.3811	$1,111.39	$1,111.40	$1,111.50