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	$62.37	7.491%	$67.0421	$67.04	$67.05	$67.00
Purchase #2	$47.48	7.496%	$51.0391	$51.04	$51.05	$51.00
Purchase #3	$30.80	4.602%	$32.2174	$32.22	$32.20	$32.20
Purchase #4	$206.61	5.779%	$218.55	$218.55	$218.55	$218.60
Purchase #5	$38.44	13.445%	$43.6083	$43.61	$43.60	$43.60
Purchase #6	$37.60	5.751%	$39.7624	$39.76	$39.75	$39.80
Purchase #7	$227.39	4.367%	$237.3201	$237.32	$237.30	$237.30
7 purchase totals =	$650.69		$689.5394	$689.54	$689.50	$689.50