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	$241.27	5.168%	$253.7388	$253.74	$253.75	$253.70
Purchase #2	$137.90	3.611%	$142.8796	$142.88	$142.90	$142.90
Purchase #3	$100.65	11.136%	$111.8584	$111.86	$111.85	$111.90
Purchase #4	$123.30	13.769%	$140.2772	$140.28	$140.30	$140.30
Purchase #5	$121.98	3.655%	$126.4384	$126.44	$126.45	$126.40
Purchase #6	$191.37	10.861%	$212.1547	$212.15	$212.15	$212.20
Purchase #7	$27.31	7.422%	$29.3369	$29.34	$29.35	$29.30
7 purchase totals =	$943.78		$1,016.6840	$1,016.69	$1,016.75	$1,016.70