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	$187.42	11.534%	$209.037	$209.04	$209.05	$209.00
Purchase #2	$111.49	11.553%	$124.3704	$124.37	$124.35	$124.40
Purchase #3	$116.89	8.842%	$127.2254	$127.23	$127.25	$127.20
Purchase #4	$90.98	13.835%	$103.5671	$103.57	$103.55	$103.60
Purchase #5	$93.60	13.615%	$106.3436	$106.34	$106.35	$106.30
Purchase #6	$190.60	5.266%	$200.637	$200.64	$200.65	$200.60
Purchase #7	$214.57	10.465%	$237.0248	$237.02	$237.00	$237.00
7 purchase totals =	$1,005.55		$1,108.2053	$1,108.21	$1,108.20	$1,108.10