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	$79.83	7.686%	$85.9657	$85.97	$85.95	$86.00
Purchase #2	$102.32	8.621%	$111.141	$111.14	$111.15	$111.10
Purchase #3	$99.41	8.730%	$108.0885	$108.09	$108.10	$108.10
Purchase #4	$65.90	8.382%	$71.4237	$71.42	$71.40	$71.40
Purchase #5	$179.41	13.677%	$203.9479	$203.95	$203.95	$203.90
Purchase #6	$198.99	5.313%	$209.5623	$209.56	$209.55	$209.60
Purchase #7	$94.90	7.321%	$101.8476	$101.85	$101.85	$101.80
7 purchase totals =	$820.76		$891.9767	$891.98	$891.95	$891.90