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	$186.64	5.395%	$196.7092	$196.71	$196.70	$196.70
Purchase #2	$218.47	12.367%	$245.4882	$245.49	$245.50	$245.50
Purchase #3	$51.91	5.556%	$54.7941	$54.79	$54.80	$54.80
Purchase #4	$180.42	13.761%	$205.2476	$205.25	$205.25	$205.20
Purchase #5	$50.57	7.448%	$54.3365	$54.34	$54.35	$54.30
Purchase #6	$226.35	13.643%	$257.2309	$257.23	$257.25	$257.20
Purchase #7	$43.74	3.465%	$45.2556	$45.26	$45.25	$45.30
7 purchase totals =	$958.10		$1,059.0621	$1,059.07	$1,059.10	$1,059.00