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	$119.75	10.805%	$132.689	$132.69	$132.70	$132.70
Purchase #2	$172.96	5.230%	$182.0058	$182.01	$182.00	$182.00
Purchase #3	$102.71	8.613%	$111.5564	$111.56	$111.55	$111.60
Purchase #4	$249.56	7.280%	$267.728	$267.73	$267.75	$267.70
Purchase #5	$72.48	8.726%	$78.8046	$78.80	$78.80	$78.80
Purchase #6	$130.71	11.763%	$146.0854	$146.09	$146.10	$146.10
Purchase #7	$131.45	7.413%	$141.1944	$141.19	$141.20	$141.20
7 purchase totals =	$979.62		$1,060.0636	$1,060.07	$1,060.10	$1,060.10