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	$113.73	5.264%	$119.7167	$119.72	$119.70	$119.70
Purchase #2	$19.65	11.432%	$21.8964	$21.90	$21.90	$21.90
Purchase #3	$33.56	4.533%	$35.0813	$35.08	$35.10	$35.10
Purchase #4	$241.87	3.579%	$250.5265	$250.53	$250.55	$250.50
Purchase #5	$139.83	11.589%	$156.0349	$156.03	$156.05	$156.00
Purchase #6	$177.90	6.133%	$188.8106	$188.81	$188.80	$188.80
Purchase #7	$242.94	5.597%	$256.5374	$256.54	$256.55	$256.50
7 purchase totals =	$969.48		$1,028.6038	$1,028.61	$1,028.65	$1,028.50