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	$230.41	9.344%	$251.9395	$251.94	$251.95	$251.90
Purchase #2	$115.55	13.734%	$131.4196	$131.42	$131.40	$131.40
Purchase #3	$52.29	3.300%	$54.0156	$54.02	$54.00	$54.00
Purchase #4	$166.96	11.578%	$186.2906	$186.29	$186.30	$186.30
Purchase #5	$174.60	6.306%	$185.6103	$185.61	$185.60	$185.60
Purchase #6	$57.50	7.847%	$62.012	$62.01	$62.00	$62.00
Purchase #7	$180.78	9.800%	$198.4964	$198.50	$198.50	$198.50
7 purchase totals =	$978.09		$1,069.7840	$1,069.79	$1,069.75	$1,069.70