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	$171.34	11.153%	$190.4496	$190.45	$190.45	$190.40
Purchase #2	$13.38	3.210%	$13.8095	$13.81	$13.80	$13.80
Purchase #3	$232.46	12.471%	$261.4501	$261.45	$261.45	$261.50
Purchase #4	$166.70	3.122%	$171.9044	$171.90	$171.90	$171.90
Purchase #5	$158.73	10.486%	$175.3744	$175.37	$175.35	$175.40
Purchase #6	$143.78	10.453%	$158.8093	$158.81	$158.80	$158.80
Purchase #7	$247.37	3.680%	$256.4732	$256.47	$256.45	$256.50
7 purchase totals =	$1,133.76		$1,228.2705	$1,228.26	$1,228.20	$1,228.30