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	$82.60	13.321%	$93.6031	$93.60	$93.60	$93.60
Purchase #2	$101.42	13.205%	$114.8125	$114.81	$114.80	$114.80
Purchase #3	$190.55	13.514%	$216.3009	$216.30	$216.30	$216.30
Purchase #4	$192.41	4.269%	$200.624	$200.62	$200.60	$200.60
Purchase #5	$46.53	4.464%	$48.6071	$48.61	$48.60	$48.60
Purchase #6	$200.73	3.768%	$208.2935	$208.29	$208.30	$208.30
Purchase #7	$168.44	12.496%	$189.4883	$189.49	$189.50	$189.50
7 purchase totals =	$982.68		$1,071.7294	$1,071.72	$1,071.70	$1,071.70