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	$152.53	10.469%	$168.4984	$168.50	$168.50	$168.50
Purchase #2	$83.45	4.222%	$86.9733	$86.97	$86.95	$87.00
Purchase #3	$66.59	7.811%	$71.7913	$71.79	$71.80	$71.80
Purchase #4	$208.79	12.452%	$234.7885	$234.79	$234.80	$234.80
Purchase #5	$134.40	12.240%	$150.8506	$150.85	$150.85	$150.90
Purchase #6	$141.51	7.359%	$151.9237	$151.92	$151.90	$151.90
Purchase #7	$151.84	6.803%	$162.1697	$162.17	$162.15	$162.20
7 purchase totals =	$939.11		$1,026.9955	$1,026.99	$1,026.95	$1,027.10