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	$200.65	7.678%	$216.0559	$216.06	$216.05	$216.10
Purchase #2	$217.98	10.848%	$241.6265	$241.63	$241.65	$241.60
Purchase #3	$54.57	13.331%	$61.8447	$61.84	$61.85	$61.80
Purchase #4	$110.32	11.495%	$123.0013	$123.00	$123.00	$123.00
Purchase #5	$213.60	7.364%	$229.3295	$229.33	$229.35	$229.30
Purchase #6	$56.38	5.509%	$59.486	$59.49	$59.50	$59.50
Purchase #7	$119.95	12.591%	$135.0529	$135.05	$135.05	$135.10
7 purchase totals =	$973.45		$1,066.3968	$1,066.40	$1,066.45	$1,066.40