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	$205.30	5.342%	$216.2671	$216.27	$216.25	$216.30
Purchase #2	$33.66	13.760%	$38.2916	$38.29	$38.30	$38.30
Purchase #3	$152.83	6.323%	$162.4934	$162.49	$162.50	$162.50
Purchase #4	$105.64	11.649%	$117.946	$117.95	$117.95	$117.90
Purchase #5	$200.82	7.797%	$216.4779	$216.48	$216.50	$216.50
Purchase #6	$207.54	5.430%	$218.8094	$218.81	$218.80	$218.80
Purchase #7	$91.85	6.187%	$97.5328	$97.53	$97.55	$97.50
7 purchase totals =	$997.64		$1,067.8182	$1,067.82	$1,067.85	$1,067.80