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	$208.59	7.475%	$224.1821	$224.18	$224.20	$224.20
Purchase #2	$116.93	5.274%	$123.0969	$123.10	$123.10	$123.10
Purchase #3	$213.54	11.268%	$237.6017	$237.60	$237.60	$237.60
Purchase #4	$86.81	12.408%	$97.5814	$97.58	$97.60	$97.60
Purchase #5	$71.92	8.526%	$78.0519	$78.05	$78.05	$78.10
Purchase #6	$154.60	7.667%	$166.4532	$166.45	$166.45	$166.50
Purchase #7	$141.61	11.193%	$157.4604	$157.46	$157.45	$157.50
7 purchase totals =	$994.00		$1,084.4276	$1,084.42	$1,084.45	$1,084.60