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	$213.85	10.139%	$235.5323	$235.53	$235.55	$235.50
Purchase #2	$84.60	7.161%	$90.6582	$90.66	$90.65	$90.70
Purchase #3	$250.74	10.299%	$276.5637	$276.56	$276.55	$276.60
Purchase #4	$103.60	13.479%	$117.5642	$117.56	$117.55	$117.60
Purchase #5	$135.61	12.437%	$152.4758	$152.48	$152.50	$152.50
Purchase #6	$117.71	12.567%	$132.5026	$132.50	$132.50	$132.50
Purchase #7	$225.86	3.172%	$233.0243	$233.02	$233.00	$233.00
7 purchase totals =	$1,131.97		$1,238.3211	$1,238.31	$1,238.30	$1,238.40