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	$72.56	4.660%	$75.9413	$75.94	$75.95	$75.90
Purchase #2	$12.83	4.823%	$13.4488	$13.45	$13.45	$13.40
Purchase #3	$152.67	7.126%	$163.5493	$163.55	$163.55	$163.50
Purchase #4	$78.33	6.683%	$83.5648	$83.56	$83.55	$83.60
Purchase #5	$74.41	5.473%	$78.4825	$78.48	$78.50	$78.50
Purchase #6	$164.63	4.431%	$171.9248	$171.92	$171.90	$171.90
Purchase #7	$114.56	3.352%	$118.4001	$118.40	$118.40	$118.40
7 purchase totals =	$669.99		$705.3116	$705.30	$705.30	$705.20