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	$43.97	3.148%	$45.3542	$45.35	$45.35	$45.40
Purchase #2	$202.92	4.393%	$211.8343	$211.83	$211.85	$211.80
Purchase #3	$146.71	12.364%	$164.8492	$164.85	$164.85	$164.80
Purchase #4	$148.46	8.784%	$161.5007	$161.50	$161.50	$161.50
Purchase #5	$150.95	9.106%	$164.6955	$164.70	$164.70	$164.70
Purchase #6	$53.55	5.784%	$56.6473	$56.65	$56.65	$56.60
Purchase #7	$205.34	7.360%	$220.453	$220.45	$220.45	$220.50
7 purchase totals =	$951.90		$1,025.3342	$1,025.33	$1,025.35	$1,025.30