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	$40.70	5.547%	$42.9576	$42.96	$42.95	$43.00
Purchase #2	$79.88	3.185%	$82.4242	$82.42	$82.40	$82.40
Purchase #3	$199.55	4.452%	$208.434	$208.43	$208.45	$208.40
Purchase #4	$190.31	13.775%	$216.5252	$216.53	$216.55	$216.50
Purchase #5	$187.54	3.475%	$194.057	$194.06	$194.05	$194.10
Purchase #6	$248.58	12.853%	$280.53	$280.53	$280.55	$280.50
Purchase #7	$88.27	3.197%	$91.092	$91.09	$91.10	$91.10
7 purchase totals =	$1,034.83		$1,116.0200	$1,116.02	$1,116.05	$1,116.00