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	$162.84	7.444%	$174.9618	$174.96	$174.95	$175.00
Purchase #2	$119.36	9.665%	$130.8961	$130.90	$130.90	$130.90
Purchase #3	$110.34	10.353%	$121.7635	$121.76	$121.75	$121.80
Purchase #4	$131.29	8.824%	$142.875	$142.88	$142.90	$142.90
Purchase #5	$59.70	13.125%	$67.5356	$67.54	$67.55	$67.50
Purchase #6	$187.31	11.570%	$208.9818	$208.98	$209.00	$209.00
Purchase #7	$65.62	10.388%	$72.4366	$72.44	$72.45	$72.40
7 purchase totals =	$836.46		$919.4504	$919.46	$919.50	$919.50