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	$118.54	7.335%	$127.2349	$127.23	$127.25	$127.20
Purchase #2	$249.62	11.330%	$277.9019	$277.90	$277.90	$277.90
Purchase #3	$220.72	4.872%	$231.4735	$231.47	$231.45	$231.50
Purchase #4	$147.77	12.373%	$166.0536	$166.05	$166.05	$166.10
Purchase #5	$175.60	4.600%	$183.6776	$183.68	$183.70	$183.70
Purchase #6	$41.86	13.636%	$47.568	$47.57	$47.55	$47.60
Purchase #7	$72.78	13.749%	$82.7865	$82.79	$82.80	$82.80
7 purchase totals =	$1,026.89		$1,116.6960	$1,116.69	$1,116.70	$1,116.80