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	$94.96	8.591%	$103.118	$103.12	$103.10	$103.10
Purchase #2	$29.74	11.290%	$33.0976	$33.10	$33.10	$33.10
Purchase #3	$210.61	7.202%	$225.7781	$225.78	$225.80	$225.80
Purchase #4	$167.27	8.802%	$181.9931	$181.99	$182.00	$182.00
Purchase #5	$90.76	13.293%	$102.8247	$102.82	$102.80	$102.80
Purchase #6	$195.98	10.151%	$215.8739	$215.87	$215.85	$215.90
Purchase #7	$217.47	6.605%	$231.8339	$231.83	$231.85	$231.80
7 purchase totals =	$1,006.79		$1,094.5193	$1,094.51	$1,094.50	$1,094.50