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	$211.57	6.768%	$225.8891	$225.89	$225.90	$225.90
Purchase #2	$172.68	5.143%	$181.5609	$181.56	$181.55	$181.60
Purchase #3	$188.83	11.507%	$210.5587	$210.56	$210.55	$210.60
Purchase #4	$238.46	3.634%	$247.1256	$247.13	$247.15	$247.10
Purchase #5	$71.85	12.183%	$80.6035	$80.60	$80.60	$80.60
Purchase #6	$8.50	3.830%	$8.8256	$8.83	$8.85	$8.80
Purchase #7	$134.93	3.483%	$139.6296	$139.63	$139.65	$139.60
7 purchase totals =	$1,026.82		$1,094.1930	$1,094.20	$1,094.25	$1,094.20