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	$59.40	10.612%	$65.7035	$65.70	$65.70	$65.70
Purchase #2	$109.34	7.741%	$117.804	$117.80	$117.80	$117.80
Purchase #3	$207.85	12.796%	$234.4465	$234.45	$234.45	$234.40
Purchase #4	$222.84	12.445%	$250.5724	$250.57	$250.55	$250.60
Purchase #5	$150.26	3.615%	$155.6919	$155.69	$155.70	$155.70
Purchase #6	$39.65	3.234%	$40.9323	$40.93	$40.95	$40.90
Purchase #7	$131.60	10.573%	$145.5141	$145.51	$145.50	$145.50
7 purchase totals =	$920.94		$1,010.6647	$1,010.65	$1,010.65	$1,010.60