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	$226.70	4.455%	$236.7995	$236.80	$236.80	$236.80
Purchase #2	$100.45	4.169%	$104.6378	$104.64	$104.65	$104.60
Purchase #3	$154.42	3.574%	$159.939	$159.94	$159.95	$159.90
Purchase #4	$236.83	8.390%	$256.7	$256.70	$256.70	$256.70
Purchase #5	$177.63	10.457%	$196.2048	$196.20	$196.20	$196.20
Purchase #6	$75.56	13.776%	$85.9691	$85.97	$85.95	$86.00
Purchase #7	$66.34	7.687%	$71.4396	$71.44	$71.45	$71.40
7 purchase totals =	$1,037.93		$1,111.6898	$1,111.69	$1,111.70	$1,111.60