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	$117.94	7.119%	$126.3361	$126.34	$126.35	$126.30
Purchase #2	$247.32	6.756%	$264.0289	$264.03	$264.05	$264.00
Purchase #3	$41.65	11.551%	$46.461	$46.46	$46.45	$46.50
Purchase #4	$60.59	8.107%	$65.502	$65.50	$65.50	$65.50
Purchase #5	$39.58	10.177%	$43.6081	$43.61	$43.60	$43.60
Purchase #6	$196.58	9.649%	$215.548	$215.55	$215.55	$215.50
Purchase #7	$231.70	11.262%	$257.7941	$257.79	$257.80	$257.80
7 purchase totals =	$935.36		$1,019.2782	$1,019.28	$1,019.30	$1,019.20