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	$47.55	10.701%	$52.6383	$52.64	$52.65	$52.60
Purchase #2	$52.31	5.873%	$55.3822	$55.38	$55.40	$55.40
Purchase #3	$92.84	3.801%	$96.3688	$96.37	$96.35	$96.40
Purchase #4	$110.99	7.570%	$119.3919	$119.39	$119.40	$119.40
Purchase #5	$200.45	3.296%	$207.0568	$207.06	$207.05	$207.10
Purchase #6	$231.75	10.804%	$256.7883	$256.79	$256.80	$256.80
Purchase #7	$241.98	13.152%	$273.8052	$273.81	$273.80	$273.80
7 purchase totals =	$977.87		$1,061.4315	$1,061.44	$1,061.45	$1,061.50