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	$186.40	5.363%	$196.3966	$196.40	$196.40	$196.40
Purchase #2	$245.91	6.874%	$262.8139	$262.81	$262.80	$262.80
Purchase #3	$51.53	10.260%	$56.817	$56.82	$56.80	$56.80
Purchase #4	$79.43	12.761%	$89.5661	$89.57	$89.55	$89.60
Purchase #5	$210.43	12.242%	$236.1908	$236.19	$236.20	$236.20
Purchase #6	$188.79	4.157%	$196.638	$196.64	$196.65	$196.60
Purchase #7	$111.62	9.817%	$122.5777	$122.58	$122.60	$122.60
7 purchase totals =	$1,074.11		$1,161.0001	$1,161.01	$1,161.00	$1,161.00