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	$96.60	8.188%	$104.5096	$104.51	$104.50	$104.50
Purchase #2	$18.25	12.388%	$20.5108	$20.51	$20.50	$20.50
Purchase #3	$40.25	4.141%	$41.9168	$41.92	$41.90	$41.90
Purchase #4	$219.64	12.177%	$246.3856	$246.39	$246.40	$246.40
Purchase #5	$194.61	6.220%	$206.7147	$206.71	$206.70	$206.70
Purchase #6	$163.46	11.309%	$181.9457	$181.95	$181.95	$181.90
Purchase #7	$188.57	13.717%	$214.4361	$214.44	$214.45	$214.40
7 purchase totals =	$921.38		$1,016.4193	$1,016.43	$1,016.40	$1,016.30