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	$169.65	7.372%	$182.1566	$182.16	$182.15	$182.20
Purchase #2	$48.75	5.204%	$51.287	$51.29	$51.30	$51.30
Purchase #3	$248.56	7.341%	$266.8068	$266.81	$266.80	$266.80
Purchase #4	$178.86	9.869%	$196.5117	$196.51	$196.50	$196.50
Purchase #5	$119.42	7.863%	$128.81	$128.81	$128.80	$128.80
Purchase #6	$70.34	4.526%	$73.5236	$73.52	$73.50	$73.50
Purchase #7	$109.90	8.514%	$119.2569	$119.26	$119.25	$119.30
7 purchase totals =	$945.48		$1,018.3526	$1,018.36	$1,018.30	$1,018.40