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	$186.37	7.688%	$200.6981	$200.70	$200.70	$200.70
Purchase #2	$125.80	12.385%	$141.3803	$141.38	$141.40	$141.40
Purchase #3	$170.77	12.646%	$192.3656	$192.37	$192.35	$192.40
Purchase #4	$161.52	7.730%	$174.0055	$174.01	$174.00	$174.00
Purchase #5	$192.49	6.771%	$205.5235	$205.52	$205.50	$205.50
Purchase #6	$185.68	6.343%	$197.4577	$197.46	$197.45	$197.50
Purchase #7	$74.72	13.782%	$85.0179	$85.02	$85.00	$85.00
7 purchase totals =	$1,097.35		$1,196.4486	$1,196.46	$1,196.40	$1,196.50