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	$142.34	11.432%	$158.6123	$158.61	$158.60	$158.60
Purchase #2	$81.29	9.866%	$89.3101	$89.31	$89.30	$89.30
Purchase #3	$179.37	3.679%	$185.969	$185.97	$185.95	$186.00
Purchase #4	$128.67	3.580%	$133.2764	$133.28	$133.30	$133.30
Purchase #5	$81.92	10.536%	$90.5511	$90.55	$90.55	$90.60
Purchase #6	$158.42	11.128%	$176.049	$176.05	$176.05	$176.00
Purchase #7	$191.57	6.161%	$203.3726	$203.37	$203.35	$203.40
7 purchase totals =	$963.58		$1,037.1405	$1,037.14	$1,037.10	$1,037.20