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	$86.61	10.229%	$95.4693	$95.47	$95.45	$95.50
Purchase #2	$148.78	9.145%	$162.3859	$162.39	$162.40	$162.40
Purchase #3	$149.88	8.697%	$162.9151	$162.92	$162.90	$162.90
Purchase #4	$8.82	4.695%	$9.2341	$9.23	$9.25	$9.20
Purchase #5	$245.85	13.635%	$279.3716	$279.37	$279.35	$279.40
Purchase #6	$249.96	7.622%	$269.012	$269.01	$269.00	$269.00
Purchase #7	$205.42	12.683%	$231.4734	$231.47	$231.45	$231.50
7 purchase totals =	$1,095.32		$1,209.8614	$1,209.86	$1,209.80	$1,209.90