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	$219.39	9.721%	$240.7169	$240.72	$240.70	$240.70
Purchase #2	$76.81	10.796%	$85.1024	$85.10	$85.10	$85.10
Purchase #3	$19.92	4.855%	$20.8871	$20.89	$20.90	$20.90
Purchase #4	$106.75	8.744%	$116.0842	$116.08	$116.10	$116.10
Purchase #5	$211.54	4.413%	$220.8753	$220.88	$220.90	$220.90
Purchase #6	$158.36	13.262%	$179.3617	$179.36	$179.35	$179.40
Purchase #7	$176.37	12.517%	$198.4462	$198.45	$198.45	$198.40
7 purchase totals =	$969.14		$1,061.4738	$1,061.48	$1,061.50	$1,061.50