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	$82.73	3.464%	$85.5958	$85.60	$85.60	$85.60
Purchase #2	$182.70	4.868%	$191.5938	$191.59	$191.60	$191.60
Purchase #3	$64.95	11.297%	$72.2874	$72.29	$72.30	$72.30
Purchase #4	$217.57	13.277%	$246.4568	$246.46	$246.45	$246.50
Purchase #5	$11.80	8.144%	$12.761	$12.76	$12.75	$12.80
Purchase #6	$182.96	13.580%	$207.806	$207.81	$207.80	$207.80
Purchase #7	$197.71	11.129%	$219.7131	$219.71	$219.70	$219.70
7 purchase totals =	$940.42		$1,036.2139	$1,036.22	$1,036.20	$1,036.30