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	$177.90	9.575%	$194.9339	$194.93	$194.95	$194.90
Purchase #2	$164.76	10.848%	$182.6332	$182.63	$182.65	$182.60
Purchase #3	$63.28	6.389%	$67.323	$67.32	$67.30	$67.30
Purchase #4	$23.81	13.823%	$27.1013	$27.10	$27.10	$27.10
Purchase #5	$208.71	13.182%	$236.2222	$236.22	$236.20	$236.20
Purchase #6	$174.64	3.330%	$180.4555	$180.46	$180.45	$180.50
Purchase #7	$168.31	11.611%	$187.8525	$187.85	$187.85	$187.90
7 purchase totals =	$981.41		$1,076.5216	$1,076.51	$1,076.50	$1,076.50