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	$207.61	13.229%	$235.0747	$235.07	$235.05	$235.10
Purchase #2	$212.85	4.417%	$222.2516	$222.25	$222.25	$222.30
Purchase #3	$50.56	9.687%	$55.4577	$55.46	$55.45	$55.50
Purchase #4	$39.90	5.857%	$42.2369	$42.24	$42.25	$42.20
Purchase #5	$164.43	9.831%	$180.5951	$180.60	$180.60	$180.60
Purchase #6	$229.39	6.548%	$244.4105	$244.41	$244.40	$244.40
Purchase #7	$142.25	7.225%	$152.5276	$152.53	$152.55	$152.50
7 purchase totals =	$1,046.99		$1,132.5541	$1,132.56	$1,132.55	$1,132.60