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	$105.38	6.308%	$112.0274	$112.03	$112.05	$112.00
Purchase #2	$192.77	9.257%	$210.6147	$210.61	$210.60	$210.60
Purchase #3	$115.63	6.836%	$123.5345	$123.53	$123.55	$123.50
Purchase #4	$40.35	12.508%	$45.397	$45.40	$45.40	$45.40
Purchase #5	$96.42	4.347%	$100.6114	$100.61	$100.60	$100.60
Purchase #6	$19.74	6.870%	$21.0961	$21.10	$21.10	$21.10
Purchase #7	$106.34	5.369%	$112.0494	$112.05	$112.05	$112.00
7 purchase totals =	$676.63		$725.3305	$725.33	$725.35	$725.20