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	$226.84	9.703%	$248.8503	$248.85	$248.85	$248.90
Purchase #2	$200.82	6.384%	$213.6403	$213.64	$213.65	$213.60
Purchase #3	$75.64	3.284%	$78.124	$78.12	$78.10	$78.10
Purchase #4	$244.93	10.857%	$271.5221	$271.52	$271.50	$271.50
Purchase #5	$119.56	13.709%	$135.9505	$135.95	$135.95	$136.00
Purchase #6	$171.61	8.251%	$185.7695	$185.77	$185.75	$185.80
Purchase #7	$78.87	4.680%	$82.5611	$82.56	$82.55	$82.60
7 purchase totals =	$1,118.27		$1,216.4178	$1,216.41	$1,216.35	$1,216.50