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	$68.26	11.455%	$76.0792	$76.08	$76.10	$76.10
Purchase #2	$152.76	11.211%	$169.8859	$169.89	$169.90	$169.90
Purchase #3	$126.73	13.181%	$143.4343	$143.43	$143.45	$143.40
Purchase #4	$147.82	12.355%	$166.0832	$166.08	$166.10	$166.10
Purchase #5	$178.95	9.853%	$196.5819	$196.58	$196.60	$196.60
Purchase #6	$209.81	3.731%	$217.638	$217.64	$217.65	$217.60
Purchase #7	$203.53	9.525%	$222.9162	$222.92	$222.90	$222.90
7 purchase totals =	$1,087.86		$1,192.6187	$1,192.62	$1,192.70	$1,192.60