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	$85.35	10.466%	$94.2827	$94.28	$94.30	$94.30
Purchase #2	$102.26	10.772%	$113.2754	$113.28	$113.30	$113.30
Purchase #3	$15.97	13.582%	$18.139	$18.14	$18.15	$18.10
Purchase #4	$241.54	3.405%	$249.7644	$249.76	$249.75	$249.80
Purchase #5	$237.31	11.299%	$264.1237	$264.12	$264.10	$264.10
Purchase #6	$106.51	9.429%	$116.5528	$116.55	$116.55	$116.60
Purchase #7	$154.91	3.873%	$160.9097	$160.91	$160.90	$160.90
7 purchase totals =	$943.85		$1,017.0477	$1,017.04	$1,017.05	$1,017.10