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	$226.71	7.780%	$244.348	$244.35	$244.35	$244.30
Purchase #2	$137.88	10.276%	$152.0485	$152.05	$152.05	$152.00
Purchase #3	$239.76	12.552%	$269.8547	$269.85	$269.85	$269.90
Purchase #4	$97.38	3.492%	$100.7805	$100.78	$100.80	$100.80
Purchase #5	$227.49	13.614%	$258.4605	$258.46	$258.45	$258.50
Purchase #6	$247.94	9.393%	$271.229	$271.23	$271.25	$271.20
Purchase #7	$98.54	5.826%	$104.2809	$104.28	$104.30	$104.30
7 purchase totals =	$1,275.70		$1,401.0021	$1,401.00	$1,401.05	$1,401.00