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	$168.27	11.429%	$187.5016	$187.50	$187.50	$187.50
Purchase #2	$63.83	10.601%	$70.5966	$70.60	$70.60	$70.60
Purchase #3	$94.40	7.636%	$101.6084	$101.61	$101.60	$101.60
Purchase #4	$211.79	5.247%	$222.9026	$222.90	$222.90	$222.90
Purchase #5	$202.48	9.859%	$222.4425	$222.44	$222.45	$222.40
Purchase #6	$196.89	3.511%	$203.8028	$203.80	$203.80	$203.80
Purchase #7	$11.94	11.528%	$13.3164	$13.32	$13.30	$13.30
7 purchase totals =	$949.60		$1,022.1709	$1,022.17	$1,022.15	$1,022.10