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	$87.32	9.795%	$95.873	$95.87	$95.85	$95.90
Purchase #2	$51.54	6.469%	$54.8741	$54.87	$54.85	$54.90
Purchase #3	$204.42	12.451%	$229.8723	$229.87	$229.85	$229.90
Purchase #4	$51.59	4.385%	$53.8522	$53.85	$53.85	$53.90
Purchase #5	$208.78	4.537%	$218.2523	$218.25	$218.25	$218.30
Purchase #6	$101.60	9.575%	$111.3282	$111.33	$111.35	$111.30
Purchase #7	$245.81	11.603%	$274.3313	$274.33	$274.35	$274.30
7 purchase totals =	$951.06		$1,038.3834	$1,038.37	$1,038.35	$1,038.50