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	$188.95	11.193%	$210.0992	$210.10	$210.10	$210.10
Purchase #2	$222.54	8.456%	$241.358	$241.36	$241.35	$241.40
Purchase #3	$144.57	7.866%	$155.9419	$155.94	$155.95	$155.90
Purchase #4	$157.86	11.118%	$175.4109	$175.41	$175.40	$175.40
Purchase #5	$106.27	9.476%	$116.3401	$116.34	$116.35	$116.30
Purchase #6	$96.35	6.523%	$102.6349	$102.63	$102.65	$102.60
Purchase #7	$13.31	8.645%	$14.4606	$14.46	$14.45	$14.50
7 purchase totals =	$929.85		$1,016.2456	$1,016.24	$1,016.25	$1,016.20