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	$213.76	7.813%	$230.4611	$230.46	$230.45	$230.50
Purchase #2	$14.46	6.508%	$15.4011	$15.40	$15.40	$15.40
Purchase #3	$238.81	6.573%	$254.507	$254.51	$254.50	$254.50
Purchase #4	$230.97	4.475%	$241.3059	$241.31	$241.30	$241.30
Purchase #5	$11.50	7.471%	$12.3592	$12.36	$12.35	$12.40
Purchase #6	$178.30	11.390%	$198.6084	$198.61	$198.60	$198.60
Purchase #7	$48.28	4.168%	$50.2923	$50.29	$50.30	$50.30
7 purchase totals =	$936.08		$1,002.9350	$1,002.94	$1,002.90	$1,003.00