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	$177.95	10.434%	$196.5173	$196.52	$196.50	$196.50
Purchase #2	$37.85	9.380%	$41.4003	$41.40	$41.40	$41.40
Purchase #3	$164.58	9.660%	$180.4784	$180.48	$180.50	$180.50
Purchase #4	$38.26	11.356%	$42.6048	$42.60	$42.60	$42.60
Purchase #5	$247.48	6.104%	$262.5862	$262.59	$262.60	$262.60
Purchase #6	$241.25	9.465%	$264.0843	$264.08	$264.10	$264.10
Purchase #7	$75.26	6.372%	$80.0556	$80.06	$80.05	$80.10
7 purchase totals =	$982.63		$1,067.7269	$1,067.73	$1,067.75	$1,067.80