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	$218.97	7.863%	$236.1876	$236.19	$236.20	$236.20
Purchase #2	$234.71	11.183%	$260.9576	$260.96	$260.95	$261.00
Purchase #3	$54.78	4.672%	$57.3393	$57.34	$57.35	$57.30
Purchase #4	$137.31	12.602%	$154.6138	$154.61	$154.60	$154.60
Purchase #5	$174.67	11.745%	$195.185	$195.19	$195.20	$195.20
Purchase #6	$85.95	4.786%	$90.0636	$90.06	$90.05	$90.10
Purchase #7	$60.28	11.603%	$67.2743	$67.27	$67.25	$67.30
7 purchase totals =	$966.67		$1,061.6212	$1,061.62	$1,061.60	$1,061.70