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	$223.91	5.293%	$235.7616	$235.76	$235.75	$235.80
Purchase #2	$44.89	11.610%	$50.1017	$50.10	$50.10	$50.10
Purchase #3	$52.65	13.651%	$59.8373	$59.84	$59.85	$59.80
Purchase #4	$168.32	4.299%	$175.5561	$175.56	$175.55	$175.60
Purchase #5	$56.67	12.681%	$63.8563	$63.86	$63.85	$63.90
Purchase #6	$149.72	12.431%	$168.3317	$168.33	$168.35	$168.30
Purchase #7	$237.66	8.320%	$257.4333	$257.43	$257.45	$257.40
7 purchase totals =	$933.82		$1,010.8780	$1,010.88	$1,010.90	$1,010.90