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	$184.45	13.167%	$208.7365	$208.74	$208.75	$208.70
Purchase #2	$186.43	13.437%	$211.4806	$211.48	$211.50	$211.50
Purchase #3	$150.85	10.790%	$167.1267	$167.13	$167.15	$167.10
Purchase #4	$203.76	5.724%	$215.4232	$215.42	$215.40	$215.40
Purchase #5	$180.29	6.241%	$191.5419	$191.54	$191.55	$191.50
Purchase #6	$40.98	10.669%	$45.3522	$45.35	$45.35	$45.40
Purchase #7	$65.74	6.846%	$70.2406	$70.24	$70.25	$70.20
7 purchase totals =	$1,012.50		$1,109.9017	$1,109.90	$1,109.95	$1,109.80