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	$212.47	7.289%	$227.9569	$227.96	$227.95	$228.00
Purchase #2	$214.37	5.607%	$226.3897	$226.39	$226.40	$226.40
Purchase #3	$141.33	10.652%	$156.3845	$156.38	$156.40	$156.40
Purchase #4	$167.55	4.803%	$175.5974	$175.60	$175.60	$175.60
Purchase #5	$27.51	12.708%	$31.006	$31.01	$31.00	$31.00
Purchase #6	$227.39	12.281%	$255.3158	$255.32	$255.30	$255.30
Purchase #7	$88.69	6.372%	$94.3413	$94.34	$94.35	$94.30
7 purchase totals =	$1,079.31		$1,166.9916	$1,167.00	$1,167.00	$1,167.00