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	$195.26	9.826%	$214.4462	$214.45	$214.45	$214.40
Purchase #2	$196.77	13.570%	$223.4717	$223.47	$223.45	$223.50
Purchase #3	$133.80	3.499%	$138.4817	$138.48	$138.50	$138.50
Purchase #4	$186.45	11.818%	$208.4847	$208.48	$208.50	$208.50
Purchase #5	$74.52	5.866%	$78.8913	$78.89	$78.90	$78.90
Purchase #6	$159.25	4.737%	$166.7937	$166.79	$166.80	$166.80
Purchase #7	$235.84	10.562%	$260.7494	$260.75	$260.75	$260.70
7 purchase totals =	$1,181.89		$1,291.3187	$1,291.31	$1,291.35	$1,291.30