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	$167.92	11.526%	$187.2745	$187.27	$187.25	$187.30
Purchase #2	$168.37	9.676%	$184.6615	$184.66	$184.65	$184.70
Purchase #3	$162.69	9.558%	$178.2399	$178.24	$178.25	$178.20
Purchase #4	$214.89	5.801%	$227.3558	$227.36	$227.35	$227.40
Purchase #5	$97.58	11.748%	$109.0437	$109.04	$109.05	$109.00
Purchase #6	$74.61	5.289%	$78.5561	$78.56	$78.55	$78.60
Purchase #7	$185.47	9.534%	$203.1527	$203.15	$203.15	$203.20
7 purchase totals =	$1,071.53		$1,168.2842	$1,168.28	$1,168.25	$1,168.40