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	$62.64	5.451%	$66.0545	$66.05	$66.05	$66.10
Purchase #2	$67.34	12.134%	$75.511	$75.51	$75.50	$75.50
Purchase #3	$93.75	10.395%	$103.4953	$103.50	$103.50	$103.50
Purchase #4	$225.92	4.667%	$236.4637	$236.46	$236.45	$236.50
Purchase #5	$219.49	9.750%	$240.8903	$240.89	$240.90	$240.90
Purchase #6	$158.62	5.295%	$167.0189	$167.02	$167.00	$167.00
Purchase #7	$136.29	11.811%	$152.3872	$152.39	$152.40	$152.40
7 purchase totals =	$964.05		$1,041.8209	$1,041.82	$1,041.80	$1,041.90