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	$66.34	8.466%	$71.9563	$71.96	$71.95	$72.00
Purchase #2	$138.37	10.138%	$152.398	$152.40	$152.40	$152.40
Purchase #3	$186.51	7.741%	$200.9477	$200.95	$200.95	$200.90
Purchase #4	$89.61	8.184%	$96.9437	$96.94	$96.95	$96.90
Purchase #5	$188.98	11.323%	$210.3782	$210.38	$210.40	$210.40
Purchase #6	$103.89	11.315%	$115.6452	$115.65	$115.65	$115.60
Purchase #7	$230.60	13.157%	$260.94	$260.94	$260.95	$260.90
7 purchase totals =	$1,004.30		$1,109.2091	$1,109.22	$1,109.25	$1,109.10