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	$213.29	8.375%	$231.153	$231.15	$231.15	$231.20
Purchase #2	$209.79	13.453%	$238.013	$238.01	$238.00	$238.00
Purchase #3	$187.94	11.176%	$208.9442	$208.94	$208.95	$208.90
Purchase #4	$184.47	6.545%	$196.5436	$196.54	$196.55	$196.50
Purchase #5	$231.34	3.834%	$240.2096	$240.21	$240.20	$240.20
Purchase #6	$191.66	9.159%	$209.2141	$209.21	$209.20	$209.20
Purchase #7	$35.61	9.300%	$38.9217	$38.92	$38.90	$38.90
7 purchase totals =	$1,254.10		$1,362.9992	$1,362.98	$1,362.95	$1,362.90