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	$148.97	8.280%	$161.3047	$161.30	$161.30	$161.30
Purchase #2	$240.94	11.635%	$268.9734	$268.97	$268.95	$269.00
Purchase #3	$11.31	4.182%	$11.783	$11.78	$11.80	$11.80
Purchase #4	$85.35	5.716%	$90.2286	$90.23	$90.25	$90.20
Purchase #5	$54.76	9.418%	$59.9173	$59.92	$59.90	$59.90
Purchase #6	$59.71	11.384%	$66.5074	$66.51	$66.50	$66.50
Purchase #7	$53.40	11.625%	$59.6078	$59.61	$59.60	$59.60
7 purchase totals =	$654.44		$718.3222	$718.32	$718.30	$718.30