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	$214.52	4.556%	$224.2935	$224.29	$224.30	$224.30
Purchase #2	$75.88	8.782%	$82.5438	$82.54	$82.55	$82.50
Purchase #3	$151.95	3.349%	$157.0388	$157.04	$157.05	$157.00
Purchase #4	$204.80	3.236%	$211.4273	$211.43	$211.45	$211.40
Purchase #5	$61.59	12.269%	$69.1465	$69.15	$69.15	$69.10
Purchase #6	$98.33	13.681%	$111.7825	$111.78	$111.80	$111.80
Purchase #7	$167.34	5.666%	$176.8215	$176.82	$176.80	$176.80
7 purchase totals =	$974.41		$1,033.0539	$1,033.05	$1,033.10	$1,032.90