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	$201.73	3.522%	$208.8349	$208.83	$208.85	$208.80
Purchase #2	$38.73	13.398%	$43.919	$43.92	$43.90	$43.90
Purchase #3	$110.64	4.747%	$115.8921	$115.89	$115.90	$115.90
Purchase #4	$240.45	10.349%	$265.3342	$265.33	$265.35	$265.30
Purchase #5	$72.97	12.229%	$81.8935	$81.89	$81.90	$81.90
Purchase #6	$213.75	3.632%	$221.5134	$221.51	$221.50	$221.50
Purchase #7	$209.41	3.436%	$216.6053	$216.61	$216.60	$216.60
7 purchase totals =	$1,087.68		$1,153.9924	$1,153.98	$1,154.00	$1,153.90