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	$65.29	11.272%	$72.6495	$72.65	$72.65	$72.60
Purchase #2	$72.50	10.548%	$80.1473	$80.15	$80.15	$80.10
Purchase #3	$100.82	3.126%	$103.9716	$103.97	$103.95	$104.00
Purchase #4	$158.31	5.337%	$166.759	$166.76	$166.75	$166.80
Purchase #5	$80.39	6.664%	$85.7472	$85.75	$85.75	$85.70
Purchase #6	$168.86	8.327%	$182.921	$182.92	$182.90	$182.90
Purchase #7	$31.92	3.481%	$33.0311	$33.03	$33.05	$33.00
7 purchase totals =	$678.09		$725.2267	$725.23	$725.20	$725.10