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	$208.81	7.736%	$224.9635	$224.96	$224.95	$225.00
Purchase #2	$193.47	3.713%	$200.6535	$200.65	$200.65	$200.70
Purchase #3	$42.49	3.345%	$43.9113	$43.91	$43.90	$43.90
Purchase #4	$155.85	6.419%	$165.854	$165.85	$165.85	$165.90
Purchase #5	$178.69	9.291%	$195.2921	$195.29	$195.30	$195.30
Purchase #6	$132.80	7.266%	$142.4492	$142.45	$142.45	$142.40
Purchase #7	$99.56	3.866%	$103.409	$103.41	$103.40	$103.40
7 purchase totals =	$1,011.67		$1,076.5326	$1,076.52	$1,076.50	$1,076.60