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	$249.96	9.459%	$273.6037	$273.60	$273.60	$273.60
Purchase #2	$44.67	5.169%	$46.979	$46.98	$47.00	$47.00
Purchase #3	$58.63	5.848%	$62.0587	$62.06	$62.05	$62.10
Purchase #4	$86.31	13.333%	$97.8177	$97.82	$97.80	$97.80
Purchase #5	$48.71	7.644%	$52.4334	$52.43	$52.45	$52.40
Purchase #6	$248.82	13.179%	$281.612	$281.61	$281.60	$281.60
Purchase #7	$216.43	13.119%	$244.8235	$244.82	$244.80	$244.80
7 purchase totals =	$953.53		$1,059.3280	$1,059.32	$1,059.30	$1,059.30