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	$118.54	4.536%	$123.917	$123.92	$123.90	$123.90
Purchase #2	$40.42	6.265%	$42.9523	$42.95	$42.95	$43.00
Purchase #3	$65.92	6.425%	$70.1554	$70.16	$70.15	$70.20
Purchase #4	$91.60	10.866%	$101.5533	$101.55	$101.55	$101.60
Purchase #5	$114.81	9.392%	$125.593	$125.59	$125.60	$125.60
Purchase #6	$82.73	13.512%	$93.9085	$93.91	$93.90	$93.90
Purchase #7	$198.80	5.804%	$210.3384	$210.34	$210.35	$210.30
7 purchase totals =	$712.82		$768.4179	$768.42	$768.40	$768.50