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	$64.76	10.610%	$71.631	$71.63	$71.65	$71.60
Purchase #2	$11.86	13.229%	$13.429	$13.43	$13.45	$13.40
Purchase #3	$187.71	5.666%	$198.3456	$198.35	$198.35	$198.30
Purchase #4	$200.39	10.770%	$221.972	$221.97	$221.95	$222.00
Purchase #5	$242.51	12.768%	$273.4737	$273.47	$273.45	$273.50
Purchase #6	$151.45	5.112%	$159.1921	$159.19	$159.20	$159.20
Purchase #7	$166.46	4.826%	$174.4934	$174.49	$174.50	$174.50
7 purchase totals =	$1,025.14		$1,112.5368	$1,112.53	$1,112.55	$1,112.50