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	$192.87	9.856%	$211.8793	$211.88	$211.90	$211.90
Purchase #2	$67.45	7.420%	$72.4548	$72.45	$72.45	$72.50
Purchase #3	$136.56	4.240%	$142.3501	$142.35	$142.35	$142.40
Purchase #4	$222.91	7.686%	$240.0429	$240.04	$240.05	$240.00
Purchase #5	$220.25	13.740%	$250.5124	$250.51	$250.50	$250.50
Purchase #6	$198.72	3.638%	$205.9494	$205.95	$205.95	$205.90
Purchase #7	$248.97	13.860%	$283.4772	$283.48	$283.50	$283.50
7 purchase totals =	$1,287.73		$1,406.6661	$1,406.66	$1,406.70	$1,406.70