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	$216.70	4.403%	$226.2413	$226.24	$226.25	$226.20
Purchase #2	$81.80	4.205%	$85.2397	$85.24	$85.25	$85.20
Purchase #3	$54.69	9.462%	$59.8648	$59.86	$59.85	$59.90
Purchase #4	$213.87	3.441%	$221.2293	$221.23	$221.25	$221.20
Purchase #5	$168.60	4.717%	$176.5529	$176.55	$176.55	$176.60
Purchase #6	$104.32	6.842%	$111.4576	$111.46	$111.45	$111.50
Purchase #7	$108.83	7.459%	$116.9476	$116.95	$116.95	$116.90
7 purchase totals =	$948.81		$997.5332	$997.53	$997.55	$997.50