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	$234.82	4.353%	$245.0417	$245.04	$245.05	$245.00
Purchase #2	$221.51	3.134%	$228.4521	$228.45	$228.45	$228.50
Purchase #3	$67.80	5.572%	$71.5778	$71.58	$71.60	$71.60
Purchase #4	$109.75	5.857%	$116.1781	$116.18	$116.20	$116.20
Purchase #5	$89.71	5.206%	$94.3803	$94.38	$94.40	$94.40
Purchase #6	$163.64	7.638%	$176.1388	$176.14	$176.15	$176.10
Purchase #7	$162.43	6.258%	$172.5949	$172.59	$172.60	$172.60
7 purchase totals =	$1,049.66		$1,104.3637	$1,104.36	$1,104.45	$1,104.40