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	$189.33	3.854%	$196.6268	$196.63	$196.65	$196.60
Purchase #2	$236.37	10.404%	$260.9619	$260.96	$260.95	$261.00
Purchase #3	$103.68	7.589%	$111.5483	$111.55	$111.55	$111.50
Purchase #4	$117.61	4.401%	$122.786	$122.79	$122.80	$122.80
Purchase #5	$59.89	5.198%	$63.0031	$63.00	$63.00	$63.00
Purchase #6	$205.42	3.467%	$212.5419	$212.54	$212.55	$212.50
Purchase #7	$164.41	13.438%	$186.5034	$186.50	$186.50	$186.50
7 purchase totals =	$1,076.71		$1,153.9714	$1,153.97	$1,154.00	$1,153.90