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	$170.25	3.158%	$175.6265	$175.63	$175.65	$175.60
Purchase #2	$67.80	5.291%	$71.3873	$71.39	$71.40	$71.40
Purchase #3	$85.92	5.444%	$90.5975	$90.60	$90.60	$90.60
Purchase #4	$143.26	5.260%	$150.7955	$150.80	$150.80	$150.80
Purchase #5	$158.73	11.207%	$176.5189	$176.52	$176.50	$176.50
Purchase #6	$240.47	9.229%	$262.663	$262.66	$262.65	$262.70
Purchase #7	$110.28	5.623%	$116.481	$116.48	$116.50	$116.50
7 purchase totals =	$976.71		$1,044.0697	$1,044.08	$1,044.10	$1,044.10