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	$99.79	8.175%	$107.9478	$107.95	$107.95	$107.90
Purchase #2	$79.34	4.127%	$82.6144	$82.61	$82.60	$82.60
Purchase #3	$8.55	8.303%	$9.2599	$9.26	$9.25	$9.30
Purchase #4	$56.48	4.751%	$59.1634	$59.16	$59.15	$59.20
Purchase #5	$212.27	12.314%	$238.4089	$238.41	$238.40	$238.40
Purchase #6	$123.67	11.448%	$137.8277	$137.83	$137.85	$137.80
Purchase #7	$87.60	3.128%	$90.3401	$90.34	$90.35	$90.30
7 purchase totals =	$667.70		$725.5622	$725.56	$725.55	$725.50