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	$78.38	9.523%	$85.8441	$85.84	$85.85	$85.80
Purchase #2	$185.57	5.668%	$196.0881	$196.09	$196.10	$196.10
Purchase #3	$19.75	9.152%	$21.5575	$21.56	$21.55	$21.60
Purchase #4	$203.64	9.827%	$223.6517	$223.65	$223.65	$223.70
Purchase #5	$137.63	10.327%	$151.8431	$151.84	$151.85	$151.80
Purchase #6	$138.57	12.330%	$155.6557	$155.66	$155.65	$155.70
Purchase #7	$181.29	9.804%	$199.0637	$199.06	$199.05	$199.10
7 purchase totals =	$944.83		$1,033.7039	$1,033.70	$1,033.70	$1,033.80