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	$214.35	11.300%	$238.5716	$238.57	$238.55	$238.60
Purchase #2	$168.74	11.449%	$188.059	$188.06	$188.05	$188.10
Purchase #3	$144.76	7.343%	$155.3897	$155.39	$155.40	$155.40
Purchase #4	$110.65	6.311%	$117.6331	$117.63	$117.65	$117.60
Purchase #5	$158.85	12.633%	$178.9175	$178.92	$178.90	$178.90
Purchase #6	$49.83	3.462%	$51.5551	$51.56	$51.55	$51.60
Purchase #7	$127.41	7.328%	$136.7466	$136.75	$136.75	$136.70
7 purchase totals =	$974.59		$1,066.8726	$1,066.88	$1,066.85	$1,066.90