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	$116.32	7.867%	$125.4709	$125.47	$125.45	$125.50
Purchase #2	$165.36	12.140%	$185.4347	$185.43	$185.45	$185.40
Purchase #3	$38.38	13.459%	$43.5456	$43.55	$43.55	$43.50
Purchase #4	$198.61	3.172%	$204.9099	$204.91	$204.90	$204.90
Purchase #5	$100.78	9.692%	$110.5476	$110.55	$110.55	$110.50
Purchase #6	$149.97	4.404%	$156.5747	$156.57	$156.55	$156.60
Purchase #7	$103.65	12.258%	$116.3554	$116.36	$116.35	$116.40
7 purchase totals =	$873.07		$942.8388	$942.84	$942.80	$942.80