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	$216.96	3.362%	$224.2542	$224.25	$224.25	$224.30
Purchase #2	$214.78	4.864%	$225.2269	$225.23	$225.25	$225.20
Purchase #3	$72.36	13.358%	$82.0258	$82.03	$82.05	$82.00
Purchase #4	$215.70	5.128%	$226.7611	$226.76	$226.75	$226.80
Purchase #5	$133.75	5.663%	$141.3243	$141.32	$141.30	$141.30
Purchase #6	$101.40	4.119%	$105.5767	$105.58	$105.60	$105.60
Purchase #7	$91.51	4.548%	$95.6719	$95.67	$95.65	$95.70
7 purchase totals =	$1,046.46		$1,100.8409	$1,100.84	$1,100.85	$1,100.90