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	$78.52	9.118%	$85.6795	$85.68	$85.70	$85.70
Purchase #2	$117.78	3.198%	$121.5466	$121.55	$121.55	$121.50
Purchase #3	$217.81	9.851%	$239.2665	$239.27	$239.25	$239.30
Purchase #4	$244.61	7.334%	$262.5497	$262.55	$262.55	$262.50
Purchase #5	$98.86	12.784%	$111.4983	$111.50	$111.50	$111.50
Purchase #6	$98.35	3.721%	$102.0096	$102.01	$102.00	$102.00
Purchase #7	$86.47	6.139%	$91.7784	$91.78	$91.80	$91.80
7 purchase totals =	$942.40		$1,014.3286	$1,014.34	$1,014.35	$1,014.30