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	$194.81	4.116%	$202.8284	$202.83	$202.85	$202.80
Purchase #2	$69.56	12.376%	$78.1687	$78.17	$78.15	$78.20
Purchase #3	$6.32	10.111%	$6.959	$6.96	$6.95	$7.00
Purchase #4	$243.91	4.751%	$255.4982	$255.50	$255.50	$255.50
Purchase #5	$87.41	12.344%	$98.1999	$98.20	$98.20	$98.20
Purchase #6	$131.97	10.522%	$145.8559	$145.86	$145.85	$145.90
Purchase #7	$249.27	12.703%	$280.9348	$280.93	$280.95	$280.90
7 purchase totals =	$983.25		$1,068.4449	$1,068.45	$1,068.45	$1,068.50