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	$214.39	5.232%	$225.6069	$225.61	$225.60	$225.60
Purchase #2	$90.43	10.236%	$99.6864	$99.69	$99.70	$99.70
Purchase #3	$127.44	10.134%	$140.3548	$140.35	$140.35	$140.40
Purchase #4	$233.96	13.805%	$266.2582	$266.26	$266.25	$266.30
Purchase #5	$171.73	9.609%	$188.2315	$188.23	$188.25	$188.20
Purchase #6	$47.49	11.477%	$52.9404	$52.94	$52.95	$52.90
Purchase #7	$77.55	3.841%	$80.5287	$80.53	$80.55	$80.50
7 purchase totals =	$962.99		$1,053.6069	$1,053.61	$1,053.65	$1,053.60