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	$211.51	4.355%	$220.7213	$220.72	$220.70	$220.70
Purchase #2	$114.37	9.161%	$124.8474	$124.85	$124.85	$124.80
Purchase #3	$170.42	8.426%	$184.7796	$184.78	$184.80	$184.80
Purchase #4	$156.96	4.706%	$164.3465	$164.35	$164.35	$164.30
Purchase #5	$149.63	10.244%	$164.9581	$164.96	$164.95	$165.00
Purchase #6	$117.89	10.194%	$129.9077	$129.91	$129.90	$129.90
Purchase #7	$118.57	7.140%	$127.0359	$127.04	$127.05	$127.00
7 purchase totals =	$1,039.35		$1,116.5965	$1,116.61	$1,116.60	$1,116.50