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	$93.81	13.354%	$106.3374	$106.34	$106.35	$106.30
Purchase #2	$177.42	10.152%	$195.4317	$195.43	$195.45	$195.40
Purchase #3	$59.27	5.598%	$62.5879	$62.59	$62.60	$62.60
Purchase #4	$103.53	12.862%	$116.846	$116.85	$116.85	$116.80
Purchase #5	$238.96	3.824%	$248.0978	$248.10	$248.10	$248.10
Purchase #6	$148.47	12.632%	$167.2247	$167.22	$167.20	$167.20
Purchase #7	$147.67	7.326%	$158.4883	$158.49	$158.50	$158.50
7 purchase totals =	$969.13		$1,055.0138	$1,055.02	$1,055.05	$1,054.90