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	$77.29	7.338%	$82.9615	$82.96	$82.95	$83.00
Purchase #2	$215.27	12.633%	$242.4651	$242.47	$242.45	$242.50
Purchase #3	$166.86	5.800%	$176.5379	$176.54	$176.55	$176.50
Purchase #4	$20.33	5.448%	$21.4376	$21.44	$21.45	$21.40
Purchase #5	$237.92	13.560%	$270.182	$270.18	$270.20	$270.20
Purchase #6	$45.95	3.293%	$47.4631	$47.46	$47.45	$47.50
Purchase #7	$249.28	6.658%	$265.8771	$265.88	$265.90	$265.90
7 purchase totals =	$1,012.90		$1,106.9243	$1,106.93	$1,106.95	$1,107.00