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	$198.32	5.133%	$208.4998	$208.50	$208.50	$208.50
Purchase #2	$58.51	3.630%	$60.6339	$60.63	$60.65	$60.60
Purchase #3	$223.71	6.423%	$238.0789	$238.08	$238.10	$238.10
Purchase #4	$166.96	8.304%	$180.8244	$180.82	$180.80	$180.80
Purchase #5	$227.82	10.440%	$251.6044	$251.60	$251.60	$251.60
Purchase #6	$132.94	7.161%	$142.4598	$142.46	$142.45	$142.50
Purchase #7	$114.46	11.416%	$127.5268	$127.53	$127.55	$127.50
7 purchase totals =	$1,122.72		$1,209.6280	$1,209.62	$1,209.65	$1,209.60