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	$240.38	10.553%	$265.7473	$265.75	$265.75	$265.70
Purchase #2	$164.93	4.210%	$171.8736	$171.87	$171.85	$171.90
Purchase #3	$14.44	10.439%	$15.9474	$15.95	$15.95	$15.90
Purchase #4	$225.48	13.519%	$255.9626	$255.96	$255.95	$256.00
Purchase #5	$222.60	4.840%	$233.3738	$233.37	$233.35	$233.40
Purchase #6	$42.61	11.652%	$47.5749	$47.57	$47.55	$47.60
Purchase #7	$80.43	6.790%	$85.8912	$85.89	$85.90	$85.90
7 purchase totals =	$990.87		$1,076.3708	$1,076.36	$1,076.30	$1,076.40