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	$140.83	8.690%	$153.0681	$153.07	$153.05	$153.10
Purchase #2	$167.33	13.244%	$189.4912	$189.49	$189.50	$189.50
Purchase #3	$198.96	13.564%	$225.9469	$225.95	$225.95	$225.90
Purchase #4	$178.94	9.601%	$196.12	$196.12	$196.10	$196.10
Purchase #5	$57.65	5.816%	$61.0029	$61.00	$61.00	$61.00
Purchase #6	$164.95	7.774%	$177.7732	$177.77	$177.75	$177.80
Purchase #7	$102.27	9.134%	$111.6113	$111.61	$111.60	$111.60
7 purchase totals =	$1,010.93		$1,115.0136	$1,115.01	$1,114.95	$1,115.00