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	$172.84	7.186%	$185.2603	$185.26	$185.25	$185.30
Purchase #2	$13.54	7.106%	$14.5022	$14.50	$14.50	$14.50
Purchase #3	$207.79	5.302%	$218.807	$218.81	$218.80	$218.80
Purchase #4	$136.31	4.851%	$142.9224	$142.92	$142.90	$142.90
Purchase #5	$78.42	5.500%	$82.7331	$82.73	$82.75	$82.70
Purchase #6	$200.33	9.833%	$220.0284	$220.03	$220.05	$220.00
Purchase #7	$212.72	4.159%	$221.567	$221.57	$221.55	$221.60
7 purchase totals =	$1,021.95		$1,085.8204	$1,085.82	$1,085.80	$1,085.80