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	$153.80	13.826%	$175.0644	$175.06	$175.05	$175.10
Purchase #2	$151.37	4.523%	$158.2165	$158.22	$158.20	$158.20
Purchase #3	$234.93	4.393%	$245.2505	$245.25	$245.25	$245.30
Purchase #4	$245.96	6.664%	$262.3508	$262.35	$262.35	$262.40
Purchase #5	$78.82	4.164%	$82.1021	$82.10	$82.10	$82.10
Purchase #6	$12.97	11.772%	$14.4968	$14.50	$14.50	$14.50
Purchase #7	$147.80	13.590%	$167.886	$167.89	$167.90	$167.90
7 purchase totals =	$1,025.65		$1,105.3671	$1,105.37	$1,105.35	$1,105.50