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	$131.36	8.616%	$142.678	$142.68	$142.70	$142.70
Purchase #2	$51.69	5.185%	$54.3701	$54.37	$54.35	$54.40
Purchase #3	$152.89	10.110%	$168.3472	$168.35	$168.35	$168.30
Purchase #4	$153.30	12.189%	$171.9857	$171.99	$172.00	$172.00
Purchase #5	$249.31	10.520%	$275.5374	$275.54	$275.55	$275.50
Purchase #6	$56.48	5.498%	$59.5853	$59.59	$59.60	$59.60
Purchase #7	$168.49	11.114%	$187.216	$187.22	$187.20	$187.20
7 purchase totals =	$963.52		$1,059.7197	$1,059.74	$1,059.75	$1,059.70