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	$207.60	10.797%	$230.0146	$230.01	$230.00	$230.00
Purchase #2	$44.75	5.457%	$47.192	$47.19	$47.20	$47.20
Purchase #3	$180.39	8.808%	$196.2788	$196.28	$196.30	$196.30
Purchase #4	$83.51	7.212%	$89.5327	$89.53	$89.55	$89.50
Purchase #5	$180.97	10.220%	$199.4651	$199.47	$199.45	$199.50
Purchase #6	$161.89	8.139%	$175.0662	$175.07	$175.05	$175.10
Purchase #7	$87.91	13.706%	$99.9589	$99.96	$99.95	$100.00
7 purchase totals =	$947.02		$1,037.5083	$1,037.51	$1,037.50	$1,037.60