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	$213.60	3.708%	$221.5203	$221.52	$221.50	$221.50
Purchase #2	$58.99	4.257%	$61.5012	$61.50	$61.50	$61.50
Purchase #3	$171.88	13.510%	$195.101	$195.10	$195.10	$195.10
Purchase #4	$124.92	7.631%	$134.4526	$134.45	$134.45	$134.50
Purchase #5	$76.66	8.467%	$83.1508	$83.15	$83.15	$83.20
Purchase #6	$63.29	6.229%	$67.2323	$67.23	$67.25	$67.20
Purchase #7	$54.43	9.403%	$59.5481	$59.55	$59.55	$59.50
7 purchase totals =	$763.77		$822.5063	$822.50	$822.50	$822.50