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	$62.63	9.789%	$68.7609	$68.76	$68.75	$68.80
Purchase #2	$143.33	6.548%	$152.7152	$152.72	$152.70	$152.70
Purchase #3	$209.26	6.106%	$222.0374	$222.04	$222.05	$222.00
Purchase #4	$209.59	12.260%	$235.2857	$235.29	$235.30	$235.30
Purchase #5	$155.64	12.735%	$175.4608	$175.46	$175.45	$175.50
Purchase #6	$40.40	4.197%	$42.0956	$42.10	$42.10	$42.10
Purchase #7	$195.84	9.787%	$215.0069	$215.01	$215.00	$215.00
7 purchase totals =	$1,016.69		$1,111.3625	$1,111.38	$1,111.35	$1,111.40