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	$85.97	6.822%	$91.8349	$91.83	$91.85	$91.80
Purchase #2	$168.80	3.437%	$174.6017	$174.60	$174.60	$174.60
Purchase #3	$162.32	7.110%	$173.861	$173.86	$173.85	$173.90
Purchase #4	$90.34	5.864%	$95.6375	$95.64	$95.65	$95.60
Purchase #5	$60.72	6.719%	$64.7998	$64.80	$64.80	$64.80
Purchase #6	$240.29	13.378%	$272.436	$272.44	$272.45	$272.40
Purchase #7	$150.32	6.343%	$159.8548	$159.85	$159.85	$159.90
7 purchase totals =	$958.76		$1,033.0257	$1,033.02	$1,033.05	$1,033.00