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	$223.70	9.585%	$245.1416	$245.14	$245.15	$245.10
Purchase #2	$218.71	5.367%	$230.4482	$230.45	$230.45	$230.40
Purchase #3	$167.38	6.697%	$178.5894	$178.59	$178.60	$178.60
Purchase #4	$14.90	4.831%	$15.6198	$15.62	$15.60	$15.60
Purchase #5	$132.43	3.582%	$137.1736	$137.17	$137.15	$137.20
Purchase #6	$222.31	8.413%	$241.0129	$241.01	$241.00	$241.00
Purchase #7	$26.40	7.712%	$28.436	$28.44	$28.45	$28.40
7 purchase totals =	$1,005.83		$1,076.4215	$1,076.42	$1,076.40	$1,076.30