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	$205.93	13.357%	$233.4361	$233.44	$233.45	$233.40
Purchase #2	$219.37	13.444%	$248.8621	$248.86	$248.85	$248.90
Purchase #3	$188.61	6.344%	$200.5754	$200.58	$200.60	$200.60
Purchase #4	$36.56	6.761%	$39.0318	$39.03	$39.05	$39.00
Purchase #5	$68.55	4.132%	$71.3825	$71.38	$71.40	$71.40
Purchase #6	$124.80	13.103%	$141.1525	$141.15	$141.15	$141.20
Purchase #7	$224.45	5.525%	$236.8509	$236.85	$236.85	$236.90
7 purchase totals =	$1,068.27		$1,171.2913	$1,171.29	$1,171.35	$1,171.40