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	$197.90	3.860%	$205.5389	$205.54	$205.55	$205.50
Purchase #2	$188.99	4.207%	$196.9408	$196.94	$196.95	$196.90
Purchase #3	$107.89	12.187%	$121.0386	$121.04	$121.05	$121.00
Purchase #4	$109.59	7.546%	$117.8597	$117.86	$117.85	$117.90
Purchase #5	$33.98	12.773%	$38.3203	$38.32	$38.30	$38.30
Purchase #6	$237.73	3.708%	$246.545	$246.55	$246.55	$246.50
Purchase #7	$120.79	13.847%	$137.5158	$137.52	$137.50	$137.50
7 purchase totals =	$996.87		$1,063.7591	$1,063.77	$1,063.75	$1,063.60