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	$188.33	4.567%	$196.931	$196.93	$196.95	$196.90
Purchase #2	$76.93	12.724%	$86.7186	$86.72	$86.70	$86.70
Purchase #3	$5.61	5.295%	$5.907	$5.91	$5.90	$5.90
Purchase #4	$187.90	13.299%	$212.8888	$212.89	$212.90	$212.90
Purchase #5	$150.53	11.367%	$167.6407	$167.64	$167.65	$167.60
Purchase #6	$216.53	4.108%	$225.4251	$225.43	$225.45	$225.40
Purchase #7	$223.98	3.668%	$232.1956	$232.20	$232.20	$232.20
7 purchase totals =	$1,049.81		$1,127.7068	$1,127.72	$1,127.75	$1,127.60