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	$202.32	4.710%	$211.8493	$211.85	$211.85	$211.80
Purchase #2	$73.47	5.540%	$77.5402	$77.54	$77.55	$77.50
Purchase #3	$70.79	3.854%	$73.5182	$73.52	$73.50	$73.50
Purchase #4	$170.35	5.351%	$179.4654	$179.47	$179.45	$179.50
Purchase #5	$109.64	11.776%	$122.5512	$122.55	$122.55	$122.60
Purchase #6	$98.52	11.592%	$109.9404	$109.94	$109.95	$109.90
Purchase #7	$233.90	3.290%	$241.5953	$241.60	$241.60	$241.60
7 purchase totals =	$958.99		$1,016.4600	$1,016.47	$1,016.45	$1,016.40