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	$196.90	3.778%	$204.3389	$204.34	$204.35	$204.30
Purchase #2	$52.57	7.415%	$56.4681	$56.47	$56.45	$56.50
Purchase #3	$200.48	7.673%	$215.8628	$215.86	$215.85	$215.90
Purchase #4	$17.55	7.161%	$18.8068	$18.81	$18.80	$18.80
Purchase #5	$55.70	7.197%	$59.7087	$59.71	$59.70	$59.70
Purchase #6	$24.45	4.109%	$25.4547	$25.45	$25.45	$25.50
Purchase #7	$163.46	7.855%	$176.2998	$176.30	$176.30	$176.30
7 purchase totals =	$711.11		$756.9398	$756.94	$756.90	$757.00