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	$179.81	9.430%	$196.7661	$196.77	$196.75	$196.80
Purchase #2	$66.29	7.352%	$71.1636	$71.16	$71.15	$71.20
Purchase #3	$78.33	6.446%	$83.3792	$83.38	$83.40	$83.40
Purchase #4	$246.26	13.168%	$278.6875	$278.69	$278.70	$278.70
Purchase #5	$150.29	13.144%	$170.0441	$170.04	$170.05	$170.00
Purchase #6	$84.93	6.136%	$90.1413	$90.14	$90.15	$90.10
Purchase #7	$148.48	10.772%	$164.4743	$164.47	$164.45	$164.50
7 purchase totals =	$954.39		$1,054.6561	$1,054.65	$1,054.65	$1,054.70