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	$209.25	13.215%	$236.9024	$236.90	$236.90	$236.90
Purchase #2	$97.72	3.219%	$100.8656	$100.87	$100.85	$100.90
Purchase #3	$158.86	10.741%	$175.9232	$175.92	$175.90	$175.90
Purchase #4	$58.78	11.788%	$65.709	$65.71	$65.70	$65.70
Purchase #5	$215.37	6.187%	$228.6949	$228.69	$228.70	$228.70
Purchase #6	$166.27	3.755%	$172.5134	$172.51	$172.50	$172.50
Purchase #7	$82.60	4.227%	$86.0915	$86.09	$86.10	$86.10
7 purchase totals =	$988.85		$1,066.7000	$1,066.69	$1,066.65	$1,066.70