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	$160.84	11.601%	$179.499	$179.50	$179.50	$179.50
Purchase #2	$151.58	11.827%	$169.5074	$169.51	$169.50	$169.50
Purchase #3	$97.80	3.538%	$101.2602	$101.26	$101.25	$101.30
Purchase #4	$107.25	8.645%	$116.5218	$116.52	$116.50	$116.50
Purchase #5	$92.83	12.453%	$104.3901	$104.39	$104.40	$104.40
Purchase #6	$139.27	11.604%	$155.4309	$155.43	$155.45	$155.40
Purchase #7	$185.32	11.655%	$206.919	$206.92	$206.90	$206.90
7 purchase totals =	$934.89		$1,033.5284	$1,033.53	$1,033.50	$1,033.50