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	$177.86	10.436%	$196.4215	$196.42	$196.40	$196.40
Purchase #2	$203.79	9.330%	$222.8036	$222.80	$222.80	$222.80
Purchase #3	$74.86	5.316%	$78.8396	$78.84	$78.85	$78.80
Purchase #4	$85.28	12.217%	$95.6987	$95.70	$95.70	$95.70
Purchase #5	$185.45	13.193%	$209.9164	$209.92	$209.90	$209.90
Purchase #6	$35.83	12.624%	$40.3532	$40.35	$40.35	$40.40
Purchase #7	$239.36	4.436%	$249.978	$249.98	$250.00	$250.00
7 purchase totals =	$1,002.43		$1,094.0110	$1,094.01	$1,094.00	$1,094.00