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	$233.71	6.266%	$248.3543	$248.35	$248.35	$248.40
Purchase #2	$74.64	4.340%	$77.8794	$77.88	$77.90	$77.90
Purchase #3	$139.83	7.675%	$150.562	$150.56	$150.55	$150.60
Purchase #4	$134.33	11.827%	$150.2172	$150.22	$150.20	$150.20
Purchase #5	$116.45	9.465%	$127.472	$127.47	$127.45	$127.50
Purchase #6	$217.81	9.563%	$238.6392	$238.64	$238.65	$238.60
Purchase #7	$65.43	7.218%	$70.1527	$70.15	$70.15	$70.20
7 purchase totals =	$982.20		$1,063.2768	$1,063.27	$1,063.25	$1,063.40