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	$105.77	7.764%	$113.982	$113.98	$114.00	$114.00
Purchase #2	$44.69	10.547%	$49.4035	$49.40	$49.40	$49.40
Purchase #3	$50.96	13.405%	$57.7912	$57.79	$57.80	$57.80
Purchase #4	$150.97	8.788%	$164.2372	$164.24	$164.25	$164.20
Purchase #5	$113.88	8.550%	$123.6167	$123.62	$123.60	$123.60
Purchase #6	$32.82	11.303%	$36.5296	$36.53	$36.55	$36.50
Purchase #7	$86.72	4.480%	$90.6051	$90.61	$90.60	$90.60
7 purchase totals =	$585.81		$636.1653	$636.17	$636.20	$636.10