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	$209.52	9.112%	$228.6115	$228.61	$228.60	$228.60
Purchase #2	$231.84	8.482%	$251.5047	$251.50	$251.50	$251.50
Purchase #3	$12.95	5.401%	$13.6494	$13.65	$13.65	$13.60
Purchase #4	$144.39	12.555%	$162.5182	$162.52	$162.50	$162.50
Purchase #5	$69.86	12.796%	$78.7993	$78.80	$78.80	$78.80
Purchase #6	$145.99	12.502%	$164.2417	$164.24	$164.25	$164.20
Purchase #7	$126.76	7.748%	$136.5814	$136.58	$136.60	$136.60
7 purchase totals =	$941.31		$1,035.9062	$1,035.90	$1,035.90	$1,035.80