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	$200.83	3.368%	$207.594	$207.59	$207.60	$207.60
Purchase #2	$72.56	13.604%	$82.4311	$82.43	$82.45	$82.40
Purchase #3	$118.68	7.619%	$127.7222	$127.72	$127.70	$127.70
Purchase #4	$173.37	3.665%	$179.724	$179.72	$179.70	$179.70
Purchase #5	$162.65	3.821%	$168.8649	$168.86	$168.85	$168.90
Purchase #6	$220.63	11.232%	$245.4112	$245.41	$245.40	$245.40
Purchase #7	$9.62	3.769%	$9.9826	$9.98	$10.00	$10.00
7 purchase totals =	$958.34		$1,021.7300	$1,021.71	$1,021.70	$1,021.70