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	$130.31	9.399%	$142.5578	$142.56	$142.55	$142.60
Purchase #2	$162.89	13.330%	$184.6032	$184.60	$184.60	$184.60
Purchase #3	$84.32	9.105%	$91.9973	$92.00	$92.00	$92.00
Purchase #4	$78.31	4.267%	$81.6515	$81.65	$81.65	$81.70
Purchase #5	$150.71	10.370%	$166.3386	$166.34	$166.35	$166.30
Purchase #6	$245.73	10.777%	$272.2123	$272.21	$272.20	$272.20
Purchase #7	$80.44	7.586%	$86.5422	$86.54	$86.55	$86.50
7 purchase totals =	$932.71		$1,025.9029	$1,025.90	$1,025.90	$1,025.90