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	$148.25	10.684%	$164.089	$164.09	$164.10	$164.10
Purchase #2	$23.53	7.758%	$25.3555	$25.36	$25.35	$25.40
Purchase #3	$158.52	6.388%	$168.6463	$168.65	$168.65	$168.60
Purchase #4	$203.43	9.581%	$222.9206	$222.92	$222.90	$222.90
Purchase #5	$103.56	8.711%	$112.5811	$112.58	$112.60	$112.60
Purchase #6	$82.70	3.586%	$85.6656	$85.67	$85.65	$85.70
Purchase #7	$113.91	11.549%	$127.0655	$127.07	$127.05	$127.10
7 purchase totals =	$833.90		$906.3236	$906.34	$906.30	$906.40