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	$97.51	7.226%	$104.5561	$104.56	$104.55	$104.60
Purchase #2	$77.28	7.488%	$83.0667	$83.07	$83.05	$83.10
Purchase #3	$209.43	9.761%	$229.8725	$229.87	$229.85	$229.90
Purchase #4	$154.39	11.636%	$172.3548	$172.35	$172.35	$172.40
Purchase #5	$91.47	9.418%	$100.0846	$100.08	$100.10	$100.10
Purchase #6	$243.80	12.347%	$273.902	$273.90	$273.90	$273.90
Purchase #7	$235.94	11.414%	$262.8702	$262.87	$262.85	$262.90
7 purchase totals =	$1,109.82		$1,226.7069	$1,226.70	$1,226.65	$1,226.90