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	$209.72	3.189%	$216.408	$216.41	$216.40	$216.40
Purchase #2	$119.52	6.776%	$127.6187	$127.62	$127.60	$127.60
Purchase #3	$53.98	5.172%	$56.7718	$56.77	$56.75	$56.80
Purchase #4	$56.81	13.438%	$64.4441	$64.44	$64.45	$64.40
Purchase #5	$200.25	6.355%	$212.9759	$212.98	$213.00	$213.00
Purchase #6	$172.48	4.154%	$179.6448	$179.64	$179.65	$179.60
Purchase #7	$178.86	9.784%	$196.3597	$196.36	$196.35	$196.40
7 purchase totals =	$991.62		$1,054.2230	$1,054.22	$1,054.20	$1,054.20