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	$116.94	7.703%	$125.9479	$125.95	$125.95	$125.90
Purchase #2	$222.27	10.738%	$246.1374	$246.14	$246.15	$246.10
Purchase #3	$45.57	7.274%	$48.8848	$48.88	$48.90	$48.90
Purchase #4	$237.55	12.856%	$268.0894	$268.09	$268.10	$268.10
Purchase #5	$178.31	12.417%	$200.4508	$200.45	$200.45	$200.50
Purchase #6	$158.78	6.148%	$168.5418	$168.54	$168.55	$168.50
Purchase #7	$228.52	9.664%	$250.6042	$250.60	$250.60	$250.60
7 purchase totals =	$1,187.94		$1,308.6563	$1,308.65	$1,308.70	$1,308.60