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	$151.60	10.863%	$168.0683	$168.07	$168.05	$168.10
Purchase #2	$13.43	7.483%	$14.435	$14.44	$14.45	$14.40
Purchase #3	$85.30	13.564%	$96.8701	$96.87	$96.85	$96.90
Purchase #4	$226.28	8.661%	$245.8781	$245.88	$245.90	$245.90
Purchase #5	$114.33	11.787%	$127.8061	$127.81	$127.80	$127.80
Purchase #6	$99.25	8.136%	$107.325	$107.33	$107.35	$107.30
Purchase #7	$247.38	8.797%	$269.142	$269.14	$269.15	$269.10
7 purchase totals =	$937.57		$1,029.5246	$1,029.54	$1,029.55	$1,029.50