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	$205.54	6.590%	$219.0851	$219.09	$219.10	$219.10
Purchase #2	$68.27	7.629%	$73.4783	$73.48	$73.50	$73.50
Purchase #3	$136.66	4.373%	$142.6361	$142.64	$142.65	$142.60
Purchase #4	$208.84	13.534%	$237.1044	$237.10	$237.10	$237.10
Purchase #5	$119.33	6.167%	$126.6891	$126.69	$126.70	$126.70
Purchase #6	$72.32	9.159%	$78.9438	$78.94	$78.95	$78.90
Purchase #7	$193.65	7.611%	$208.3887	$208.39	$208.40	$208.40
7 purchase totals =	$1,004.61		$1,086.3255	$1,086.33	$1,086.40	$1,086.30