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	$197.31	9.267%	$215.5947	$215.59	$215.60	$215.60
Purchase #2	$127.72	9.656%	$140.0526	$140.05	$140.05	$140.10
Purchase #3	$191.83	4.288%	$200.0557	$200.06	$200.05	$200.10
Purchase #4	$36.64	5.417%	$38.6248	$38.62	$38.60	$38.60
Purchase #5	$134.65	4.227%	$140.3417	$140.34	$140.35	$140.30
Purchase #6	$176.54	7.123%	$189.1149	$189.11	$189.10	$189.10
Purchase #7	$38.65	12.760%	$43.5817	$43.58	$43.60	$43.60
7 purchase totals =	$903.34		$967.3661	$967.35	$967.35	$967.40