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	$215.40	12.322%	$241.9416	$241.94	$241.95	$241.90
Purchase #2	$190.41	3.227%	$196.5545	$196.55	$196.55	$196.60
Purchase #3	$32.49	4.167%	$33.8439	$33.84	$33.85	$33.80
Purchase #4	$213.71	3.305%	$220.7731	$220.77	$220.75	$220.80
Purchase #5	$150.42	5.520%	$158.7232	$158.72	$158.70	$158.70
Purchase #6	$170.54	5.161%	$179.3416	$179.34	$179.35	$179.30
Purchase #7	$120.91	11.294%	$134.5656	$134.57	$134.55	$134.60
7 purchase totals =	$1,093.88		$1,165.7435	$1,165.73	$1,165.70	$1,165.70