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	$185.80	6.403%	$197.6968	$197.70	$197.70	$197.70
Purchase #2	$206.28	10.187%	$227.2937	$227.29	$227.30	$227.30
Purchase #3	$9.78	7.470%	$10.5106	$10.51	$10.50	$10.50
Purchase #4	$212.74	7.338%	$228.3509	$228.35	$228.35	$228.40
Purchase #5	$189.71	3.712%	$196.752	$196.75	$196.75	$196.80
Purchase #6	$121.89	4.669%	$127.581	$127.58	$127.60	$127.60
Purchase #7	$37.38	13.663%	$42.4872	$42.49	$42.50	$42.50
7 purchase totals =	$963.58		$1,030.6722	$1,030.67	$1,030.70	$1,030.80