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	$144.87	4.547%	$151.4572	$151.46	$151.45	$151.50
Purchase #2	$95.35	5.570%	$100.661	$100.66	$100.65	$100.70
Purchase #3	$41.43	4.509%	$43.2981	$43.30	$43.30	$43.30
Purchase #4	$110.64	11.627%	$123.5041	$123.50	$123.50	$123.50
Purchase #5	$96.46	9.362%	$105.4906	$105.49	$105.50	$105.50
Purchase #6	$6.42	9.243%	$7.0134	$7.01	$7.00	$7.00
Purchase #7	$198.80	7.423%	$213.5569	$213.56	$213.55	$213.60
7 purchase totals =	$693.97		$744.9813	$744.98	$744.95	$745.10