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	$198.73	8.486%	$215.5942	$215.59	$215.60	$215.60
Purchase #2	$31.37	4.159%	$32.6747	$32.67	$32.65	$32.70
Purchase #3	$197.69	11.657%	$220.7347	$220.73	$220.75	$220.70
Purchase #4	$152.39	6.838%	$162.8104	$162.81	$162.80	$162.80
Purchase #5	$198.51	11.805%	$221.9441	$221.94	$221.95	$221.90
Purchase #6	$76.87	7.422%	$82.5753	$82.58	$82.60	$82.60
Purchase #7	$69.52	4.135%	$72.3947	$72.39	$72.40	$72.40
7 purchase totals =	$925.08		$1,008.7281	$1,008.71	$1,008.75	$1,008.70