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	$104.57	7.105%	$111.9997	$112.00	$112.00	$112.00
Purchase #2	$182.92	12.487%	$205.7612	$205.76	$205.75	$205.80
Purchase #3	$59.98	7.201%	$64.2992	$64.30	$64.30	$64.30
Purchase #4	$162.78	10.701%	$180.1991	$180.20	$180.20	$180.20
Purchase #5	$33.65	11.242%	$37.4329	$37.43	$37.45	$37.40
Purchase #6	$176.77	12.178%	$198.2971	$198.30	$198.30	$198.30
Purchase #7	$228.37	8.332%	$247.3978	$247.40	$247.40	$247.40
7 purchase totals =	$949.04		$1,045.3870	$1,045.39	$1,045.40	$1,045.40