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	$196.84	9.545%	$215.6284	$215.63	$215.65	$215.60
Purchase #2	$164.75	7.185%	$176.5873	$176.59	$176.60	$176.60
Purchase #3	$33.45	10.229%	$36.8716	$36.87	$36.85	$36.90
Purchase #4	$131.33	11.378%	$146.2727	$146.27	$146.25	$146.30
Purchase #5	$186.64	6.616%	$198.9881	$198.99	$199.00	$199.00
Purchase #6	$96.59	9.189%	$105.4657	$105.47	$105.45	$105.50
Purchase #7	$237.56	11.157%	$264.0646	$264.06	$264.05	$264.10
7 purchase totals =	$1,047.16		$1,143.8784	$1,143.88	$1,143.85	$1,144.00