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	$91.98	5.848%	$97.359	$97.36	$97.35	$97.40
Purchase #2	$43.87	11.251%	$48.8058	$48.81	$48.80	$48.80
Purchase #3	$121.41	4.652%	$127.058	$127.06	$127.05	$127.10
Purchase #4	$26.83	12.124%	$30.0829	$30.08	$30.10	$30.10
Purchase #5	$174.40	6.585%	$185.8842	$185.88	$185.90	$185.90
Purchase #6	$75.57	8.601%	$82.0698	$82.07	$82.05	$82.10
Purchase #7	$33.83	5.232%	$35.6	$35.60	$35.60	$35.60
7 purchase totals =	$567.89		$606.8597	$606.86	$606.85	$607.00