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	$198.46	13.864%	$225.9745	$225.97	$225.95	$226.00
Purchase #2	$227.69	12.258%	$255.6002	$255.60	$255.60	$255.60
Purchase #3	$6.75	6.391%	$7.1814	$7.18	$7.20	$7.20
Purchase #4	$85.85	12.343%	$96.4465	$96.45	$96.45	$96.40
Purchase #5	$221.75	4.688%	$232.1456	$232.15	$232.15	$232.10
Purchase #6	$101.93	13.825%	$116.0218	$116.02	$116.00	$116.00
Purchase #7	$115.86	10.119%	$127.5839	$127.58	$127.60	$127.60
7 purchase totals =	$958.29		$1,060.9539	$1,060.95	$1,060.95	$1,060.90