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	$240.37	7.245%	$257.7848	$257.78	$257.80	$257.80
Purchase #2	$92.63	11.271%	$103.0703	$103.07	$103.05	$103.10
Purchase #3	$31.53	4.181%	$32.8483	$32.85	$32.85	$32.80
Purchase #4	$197.35	4.815%	$206.8524	$206.85	$206.85	$206.90
Purchase #5	$246.44	11.665%	$275.1872	$275.19	$275.20	$275.20
Purchase #6	$60.78	9.401%	$66.4939	$66.49	$66.50	$66.50
Purchase #7	$74.59	10.703%	$82.5734	$82.57	$82.55	$82.60
7 purchase totals =	$943.69		$1,024.8103	$1,024.80	$1,024.80	$1,024.90