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	$211.56	11.589%	$236.0777	$236.08	$236.10	$236.10
Purchase #2	$155.77	10.748%	$172.5122	$172.51	$172.50	$172.50
Purchase #3	$184.50	6.522%	$196.5331	$196.53	$196.55	$196.50
Purchase #4	$175.78	3.661%	$182.2153	$182.22	$182.20	$182.20
Purchase #5	$233.68	6.703%	$249.3436	$249.34	$249.35	$249.30
Purchase #6	$199.42	3.604%	$206.6071	$206.61	$206.60	$206.60
Purchase #7	$206.59	10.128%	$227.5134	$227.51	$227.50	$227.50
7 purchase totals =	$1,367.30		$1,470.8024	$1,470.80	$1,470.80	$1,470.70