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	$184.28	11.593%	$205.6436	$205.64	$205.65	$205.60
Purchase #2	$88.89	11.133%	$98.7861	$98.79	$98.80	$98.80
Purchase #3	$98.48	7.452%	$105.8187	$105.82	$105.80	$105.80
Purchase #4	$195.54	9.621%	$214.3529	$214.35	$214.35	$214.40
Purchase #5	$229.83	11.165%	$255.4905	$255.49	$255.50	$255.50
Purchase #6	$146.50	8.685%	$159.2235	$159.22	$159.20	$159.20
Purchase #7	$44.46	4.232%	$46.3415	$46.34	$46.35	$46.30
7 purchase totals =	$987.98		$1,085.6568	$1,085.65	$1,085.65	$1,085.60