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	$213.97	9.557%	$234.4191	$234.42	$234.40	$234.40
Purchase #2	$7.30	4.183%	$7.6054	$7.61	$7.60	$7.60
Purchase #3	$250.59	4.445%	$261.7287	$261.73	$261.75	$261.70
Purchase #4	$220.70	11.376%	$245.8068	$245.81	$245.80	$245.80
Purchase #5	$30.55	6.551%	$32.5513	$32.55	$32.55	$32.60
Purchase #6	$116.90	12.345%	$131.3313	$131.33	$131.35	$131.30
Purchase #7	$142.79	5.223%	$150.2479	$150.25	$150.25	$150.20
7 purchase totals =	$982.80		$1,063.6905	$1,063.70	$1,063.70	$1,063.60