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	$155.58	4.512%	$162.5998	$162.60	$162.60	$162.60
Purchase #2	$62.52	7.169%	$67.0021	$67.00	$67.00	$67.00
Purchase #3	$213.79	11.140%	$237.6062	$237.61	$237.60	$237.60
Purchase #4	$52.88	12.136%	$59.2975	$59.30	$59.30	$59.30
Purchase #5	$171.27	6.368%	$182.1765	$182.18	$182.20	$182.20
Purchase #6	$33.82	7.349%	$36.3054	$36.31	$36.30	$36.30
Purchase #7	$190.80	5.272%	$200.859	$200.86	$200.85	$200.90
7 purchase totals =	$880.66		$945.8465	$945.86	$945.85	$945.90