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	$59.73	4.386%	$62.3498	$62.35	$62.35	$62.30
Purchase #2	$147.81	13.689%	$168.0437	$168.04	$168.05	$168.00
Purchase #3	$127.75	7.142%	$136.8739	$136.87	$136.85	$136.90
Purchase #4	$161.73	4.429%	$168.893	$168.89	$168.90	$168.90
Purchase #5	$38.31	4.788%	$40.1443	$40.14	$40.15	$40.10
Purchase #6	$220.37	11.349%	$245.3798	$245.38	$245.40	$245.40
Purchase #7	$207.39	9.330%	$226.7395	$226.74	$226.75	$226.70
7 purchase totals =	$963.09		$1,048.4240	$1,048.41	$1,048.45	$1,048.30