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	$236.37	4.857%	$247.8505	$247.85	$247.85	$247.90
Purchase #2	$97.37	4.314%	$101.5705	$101.57	$101.55	$101.60
Purchase #3	$176.53	13.434%	$200.245	$200.25	$200.25	$200.20
Purchase #4	$208.94	8.471%	$226.6393	$226.64	$226.65	$226.60
Purchase #5	$139.75	9.140%	$152.5232	$152.52	$152.50	$152.50
Purchase #6	$66.90	7.544%	$71.9469	$71.95	$71.95	$71.90
Purchase #7	$50.56	7.330%	$54.266	$54.27	$54.25	$54.30
7 purchase totals =	$976.42		$1,055.0414	$1,055.05	$1,055.00	$1,055.00