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	$206.87	9.723%	$226.984	$226.98	$227.00	$227.00
Purchase #2	$111.49	13.646%	$126.7039	$126.70	$126.70	$126.70
Purchase #3	$190.39	3.199%	$196.4806	$196.48	$196.50	$196.50
Purchase #4	$75.29	6.782%	$80.3962	$80.40	$80.40	$80.40
Purchase #5	$31.90	3.663%	$33.0685	$33.07	$33.05	$33.10
Purchase #6	$200.59	9.607%	$219.8607	$219.86	$219.85	$219.90
Purchase #7	$62.29	5.767%	$65.8823	$65.88	$65.90	$65.90
7 purchase totals =	$878.82		$949.3762	$949.37	$949.40	$949.50