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	$218.67	4.367%	$228.2193	$228.22	$228.20	$228.20
Purchase #2	$9.97	6.216%	$10.5897	$10.59	$10.60	$10.60
Purchase #3	$50.71	6.553%	$54.033	$54.03	$54.05	$54.00
Purchase #4	$78.50	13.421%	$89.0355	$89.04	$89.05	$89.00
Purchase #5	$180.92	13.689%	$205.6861	$205.69	$205.70	$205.70
Purchase #6	$100.82	11.196%	$112.1078	$112.11	$112.10	$112.10
Purchase #7	$100.25	9.188%	$109.461	$109.46	$109.45	$109.50
7 purchase totals =	$739.84		$809.1324	$809.14	$809.15	$809.10