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	$118.65	7.444%	$127.4823	$127.48	$127.50	$127.50
Purchase #2	$118.34	7.507%	$127.2238	$127.22	$127.20	$127.20
Purchase #3	$82.30	3.697%	$85.3426	$85.34	$85.35	$85.30
Purchase #4	$166.82	10.354%	$184.0925	$184.09	$184.10	$184.10
Purchase #5	$207.36	5.181%	$218.1033	$218.10	$218.10	$218.10
Purchase #6	$129.86	7.338%	$139.3891	$139.39	$139.40	$139.40
Purchase #7	$161.29	7.512%	$173.4061	$173.41	$173.40	$173.40
7 purchase totals =	$984.62		$1,055.0397	$1,055.03	$1,055.05	$1,055.00