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	$234.53	7.623%	$252.4082	$252.41	$252.40	$252.40
Purchase #2	$6.51	4.208%	$6.7839	$6.78	$6.80	$6.80
Purchase #3	$28.96	12.564%	$32.5985	$32.60	$32.60	$32.60
Purchase #4	$74.82	11.621%	$83.5148	$83.51	$83.50	$83.50
Purchase #5	$50.31	4.255%	$52.4507	$52.45	$52.45	$52.50
Purchase #6	$111.73	7.141%	$119.7086	$119.71	$119.70	$119.70
Purchase #7	$155.59	12.804%	$175.5117	$175.51	$175.50	$175.50
7 purchase totals =	$662.45		$722.9764	$722.97	$722.95	$723.00