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	$126.51	4.412%	$132.0916	$132.09	$132.10	$132.10
Purchase #2	$105.89	11.799%	$118.384	$118.38	$118.40	$118.40
Purchase #3	$183.53	4.314%	$191.4475	$191.45	$191.45	$191.40
Purchase #4	$86.56	10.674%	$95.7994	$95.80	$95.80	$95.80
Purchase #5	$100.44	4.401%	$104.8604	$104.86	$104.85	$104.90
Purchase #6	$199.88	5.741%	$211.3551	$211.36	$211.35	$211.40
Purchase #7	$90.55	5.824%	$95.8236	$95.82	$95.80	$95.80
7 purchase totals =	$893.36		$949.7616	$949.76	$949.75	$949.80