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	$122.37	7.615%	$131.6885	$131.69	$131.70	$131.70
Purchase #2	$59.42	13.790%	$67.614	$67.61	$67.60	$67.60
Purchase #3	$116.71	4.792%	$122.3027	$122.30	$122.30	$122.30
Purchase #4	$133.59	10.463%	$147.5675	$147.57	$147.55	$147.60
Purchase #5	$241.64	7.454%	$259.6518	$259.65	$259.65	$259.70
Purchase #6	$143.42	6.397%	$152.5946	$152.59	$152.60	$152.60
Purchase #7	$142.73	5.470%	$150.5373	$150.54	$150.55	$150.50
7 purchase totals =	$959.88		$1,031.9564	$1,031.95	$1,031.95	$1,032.00