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	$209.86	6.365%	$223.2176	$223.22	$223.20	$223.20
Purchase #2	$233.73	3.339%	$241.5342	$241.53	$241.55	$241.50
Purchase #3	$164.41	12.558%	$185.0566	$185.06	$185.05	$185.10
Purchase #4	$174.98	10.724%	$193.7449	$193.74	$193.75	$193.70
Purchase #5	$117.84	4.615%	$123.2783	$123.28	$123.30	$123.30
Purchase #6	$246.46	6.549%	$262.6007	$262.60	$262.60	$262.60
Purchase #7	$213.38	4.185%	$222.31	$222.31	$222.30	$222.30
7 purchase totals =	$1,360.66		$1,451.7423	$1,451.74	$1,451.75	$1,451.70