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	$200.87	4.477%	$209.8629	$209.86	$209.85	$209.90
Purchase #2	$47.44	8.731%	$51.582	$51.58	$51.60	$51.60
Purchase #3	$197.76	9.440%	$216.4285	$216.43	$216.45	$216.40
Purchase #4	$12.34	9.536%	$13.5167	$13.52	$13.50	$13.50
Purchase #5	$79.55	3.682%	$82.479	$82.48	$82.50	$82.50
Purchase #6	$111.27	9.382%	$121.7094	$121.71	$121.70	$121.70
Purchase #7	$159.99	7.439%	$171.8917	$171.89	$171.90	$171.90
7 purchase totals =	$809.22		$867.4702	$867.47	$867.50	$867.50