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	$196.61	13.215%	$222.592	$222.59	$222.60	$222.60
Purchase #2	$21.57	13.236%	$24.425	$24.43	$24.45	$24.40
Purchase #3	$119.78	4.798%	$125.527	$125.53	$125.55	$125.50
Purchase #4	$174.58	12.544%	$196.4793	$196.48	$196.50	$196.50
Purchase #5	$89.93	11.775%	$100.5193	$100.52	$100.50	$100.50
Purchase #6	$247.78	11.656%	$276.6612	$276.66	$276.65	$276.70
Purchase #7	$182.74	10.732%	$202.3517	$202.35	$202.35	$202.40
7 purchase totals =	$1,032.99		$1,148.5555	$1,148.56	$1,148.60	$1,148.60