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	$107.92	3.830%	$112.0533	$112.05	$112.05	$112.10
Purchase #2	$37.35	9.665%	$40.9599	$40.96	$40.95	$41.00
Purchase #3	$12.74	6.188%	$13.5284	$13.53	$13.55	$13.50
Purchase #4	$119.69	4.661%	$125.2688	$125.27	$125.25	$125.30
Purchase #5	$119.47	3.705%	$123.8964	$123.90	$123.90	$123.90
Purchase #6	$90.53	7.809%	$97.5995	$97.60	$97.60	$97.60
Purchase #7	$52.79	4.310%	$55.0652	$55.07	$55.05	$55.10
7 purchase totals =	$540.49		$568.3715	$568.38	$568.35	$568.50