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	$169.36	9.712%	$185.8082	$185.81	$185.80	$185.80
Purchase #2	$168.75	4.590%	$176.4956	$176.50	$176.50	$176.50
Purchase #3	$138.60	5.244%	$145.8682	$145.87	$145.85	$145.90
Purchase #4	$151.92	11.173%	$168.894	$168.89	$168.90	$168.90
Purchase #5	$70.63	11.610%	$78.8301	$78.83	$78.85	$78.80
Purchase #6	$69.79	8.619%	$75.8052	$75.81	$75.80	$75.80
Purchase #7	$172.40	4.184%	$179.6132	$179.61	$179.60	$179.60
7 purchase totals =	$941.45		$1,011.3145	$1,011.32	$1,011.30	$1,011.30