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	$78.93	8.377%	$85.542	$85.54	$85.55	$85.50
Purchase #2	$183.41	4.603%	$191.8524	$191.85	$191.85	$191.90
Purchase #3	$189.25	9.647%	$207.5069	$207.51	$207.50	$207.50
Purchase #4	$186.68	5.468%	$196.8877	$196.89	$196.90	$196.90
Purchase #5	$78.57	5.816%	$83.1396	$83.14	$83.15	$83.10
Purchase #6	$17.37	3.610%	$17.9971	$18.00	$18.00	$18.00
Purchase #7	$236.89	5.388%	$249.6536	$249.65	$249.65	$249.70
7 purchase totals =	$971.10		$1,032.5793	$1,032.58	$1,032.60	$1,032.60