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	$214.27	11.190%	$238.2468	$238.25	$238.25	$238.20
Purchase #2	$80.71	10.715%	$89.3581	$89.36	$89.35	$89.40
Purchase #3	$178.54	6.716%	$190.5307	$190.53	$190.55	$190.50
Purchase #4	$29.90	4.187%	$31.1519	$31.15	$31.15	$31.20
Purchase #5	$224.91	9.466%	$246.2	$246.20	$246.20	$246.20
Purchase #6	$58.36	5.861%	$61.7805	$61.78	$61.80	$61.80
Purchase #7	$158.76	3.821%	$164.8262	$164.83	$164.85	$164.80
7 purchase totals =	$945.45		$1,022.0942	$1,022.10	$1,022.15	$1,022.10