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	$103.26	10.609%	$114.2149	$114.21	$114.20	$114.20
Purchase #2	$168.85	10.433%	$186.4661	$186.47	$186.45	$186.50
Purchase #3	$203.47	12.219%	$228.332	$228.33	$228.35	$228.30
Purchase #4	$54.62	9.112%	$59.597	$59.60	$59.60	$59.60
Purchase #5	$127.92	4.460%	$133.6252	$133.63	$133.65	$133.60
Purchase #6	$82.37	7.744%	$88.7487	$88.75	$88.75	$88.70
Purchase #7	$196.42	4.456%	$205.1725	$205.17	$205.15	$205.20
7 purchase totals =	$936.91		$1,016.1564	$1,016.16	$1,016.15	$1,016.10