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	$215.75	6.491%	$229.7543	$229.75	$229.75	$229.80
Purchase #2	$211.38	5.667%	$223.3589	$223.36	$223.35	$223.40
Purchase #3	$151.67	7.230%	$162.6357	$162.64	$162.65	$162.60
Purchase #4	$204.35	6.296%	$217.2159	$217.22	$217.20	$217.20
Purchase #5	$101.67	6.769%	$108.552	$108.55	$108.55	$108.60
Purchase #6	$78.79	4.444%	$82.2914	$82.29	$82.30	$82.30
Purchase #7	$94.72	10.868%	$105.0142	$105.01	$105.00	$105.00
7 purchase totals =	$1,058.33		$1,128.8224	$1,128.82	$1,128.80	$1,128.90