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	$180.56	8.536%	$195.9726	$195.97	$195.95	$196.00
Purchase #2	$84.32	9.556%	$92.3776	$92.38	$92.40	$92.40
Purchase #3	$55.65	7.210%	$59.6624	$59.66	$59.65	$59.70
Purchase #4	$179.83	7.253%	$192.8731	$192.87	$192.85	$192.90
Purchase #5	$234.27	11.661%	$261.5882	$261.59	$261.60	$261.60
Purchase #6	$75.64	6.589%	$80.6239	$80.62	$80.60	$80.60
Purchase #7	$123.27	3.530%	$127.6214	$127.62	$127.60	$127.60
7 purchase totals =	$933.54		$1,010.7192	$1,010.71	$1,010.65	$1,010.80