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	$210.35	8.272%	$227.7502	$227.75	$227.75	$227.80
Purchase #2	$85.89	6.738%	$91.6773	$91.68	$91.70	$91.70
Purchase #3	$174.34	4.856%	$182.806	$182.81	$182.80	$182.80
Purchase #4	$105.67	10.606%	$116.8774	$116.88	$116.90	$116.90
Purchase #5	$107.67	9.813%	$118.2357	$118.24	$118.25	$118.20
Purchase #6	$100.95	4.702%	$105.6967	$105.70	$105.70	$105.70
Purchase #7	$213.49	4.243%	$222.5484	$222.55	$222.55	$222.50
7 purchase totals =	$998.36		$1,065.5917	$1,065.61	$1,065.65	$1,065.60