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	$119.68	9.414%	$130.9467	$130.95	$130.95	$130.90
Purchase #2	$71.92	3.648%	$74.5436	$74.54	$74.55	$74.50
Purchase #3	$108.67	13.523%	$123.3654	$123.37	$123.35	$123.40
Purchase #4	$152.93	12.399%	$171.8918	$171.89	$171.90	$171.90
Purchase #5	$56.72	13.632%	$64.4521	$64.45	$64.45	$64.50
Purchase #6	$49.62	12.858%	$56.0001	$56.00	$56.00	$56.00
Purchase #7	$80.49	13.119%	$91.0495	$91.05	$91.05	$91.00
7 purchase totals =	$640.03		$712.2492	$712.25	$712.25	$712.20