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	$218.88	12.362%	$245.9379	$245.94	$245.95	$245.90
Purchase #2	$70.79	10.733%	$78.3879	$78.39	$78.40	$78.40
Purchase #3	$138.97	9.817%	$152.6127	$152.61	$152.60	$152.60
Purchase #4	$79.93	8.618%	$86.8184	$86.82	$86.80	$86.80
Purchase #5	$176.80	8.181%	$191.264	$191.26	$191.25	$191.30
Purchase #6	$89.37	6.825%	$95.4695	$95.47	$95.45	$95.50
Purchase #7	$165.48	8.194%	$179.0394	$179.04	$179.05	$179.00
7 purchase totals =	$940.22		$1,029.5298	$1,029.53	$1,029.50	$1,029.50