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	$213.96	5.153%	$224.9854	$224.99	$225.00	$225.00
Purchase #2	$138.99	6.480%	$147.9966	$148.00	$148.00	$148.00
Purchase #3	$173.83	13.107%	$196.6139	$196.61	$196.60	$196.60
Purchase #4	$72.55	9.300%	$79.2972	$79.30	$79.30	$79.30
Purchase #5	$159.60	3.134%	$164.6019	$164.60	$164.60	$164.60
Purchase #6	$98.50	5.657%	$104.0721	$104.07	$104.05	$104.10
Purchase #7	$121.27	8.746%	$131.8763	$131.88	$131.90	$131.90
7 purchase totals =	$978.70		$1,049.4434	$1,049.45	$1,049.45	$1,049.50