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	$149.39	8.621%	$162.2689	$162.27	$162.25	$162.30
Purchase #2	$250.46	9.744%	$274.8648	$274.86	$274.85	$274.90
Purchase #3	$7.90	8.591%	$8.5787	$8.58	$8.60	$8.60
Purchase #4	$103.58	4.293%	$108.0267	$108.03	$108.05	$108.00
Purchase #5	$158.60	5.303%	$167.0106	$167.01	$167.00	$167.00
Purchase #6	$154.89	8.545%	$168.1254	$168.13	$168.15	$168.10
Purchase #7	$153.90	11.173%	$171.0952	$171.10	$171.10	$171.10
7 purchase totals =	$978.72		$1,059.9703	$1,059.98	$1,060.00	$1,060.00