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	$157.42	7.359%	$169.0045	$169.00	$169.00	$169.00
Purchase #2	$176.25	11.692%	$196.8572	$196.86	$196.85	$196.90
Purchase #3	$202.84	8.272%	$219.6189	$219.62	$219.60	$219.60
Purchase #4	$47.70	7.495%	$51.2751	$51.28	$51.30	$51.30
Purchase #5	$90.47	9.261%	$98.8484	$98.85	$98.85	$98.80
Purchase #6	$198.36	6.864%	$211.9754	$211.98	$212.00	$212.00
Purchase #7	$66.65	3.391%	$68.9101	$68.91	$68.90	$68.90
7 purchase totals =	$939.69		$1,016.4896	$1,016.50	$1,016.50	$1,016.50