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	$239.98	10.696%	$265.6483	$265.65	$265.65	$265.60
Purchase #2	$89.88	6.397%	$95.6296	$95.63	$95.65	$95.60
Purchase #3	$182.78	7.358%	$196.229	$196.23	$196.25	$196.20
Purchase #4	$64.82	9.391%	$70.9072	$70.91	$70.90	$70.90
Purchase #5	$80.66	6.641%	$86.0166	$86.02	$86.00	$86.00
Purchase #6	$85.75	5.643%	$90.5889	$90.59	$90.60	$90.60
Purchase #7	$209.97	3.522%	$217.3651	$217.37	$217.35	$217.40
7 purchase totals =	$953.84		$1,022.3847	$1,022.40	$1,022.40	$1,022.30