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	$181.92	10.184%	$200.4467	$200.45	$200.45	$200.40
Purchase #2	$210.64	6.413%	$224.1483	$224.15	$224.15	$224.10
Purchase #3	$174.31	9.779%	$191.3558	$191.36	$191.35	$191.40
Purchase #4	$10.79	7.336%	$11.5816	$11.58	$11.60	$11.60
Purchase #5	$97.82	11.471%	$109.0409	$109.04	$109.05	$109.00
Purchase #6	$165.54	11.724%	$184.9479	$184.95	$184.95	$184.90
Purchase #7	$125.86	6.504%	$134.0459	$134.05	$134.05	$134.00
7 purchase totals =	$966.88		$1,055.5671	$1,055.58	$1,055.60	$1,055.40