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	$186.75	5.382%	$196.8009	$196.80	$196.80	$196.80
Purchase #2	$125.79	6.597%	$134.0884	$134.09	$134.10	$134.10
Purchase #3	$182.75	10.375%	$201.7103	$201.71	$201.70	$201.70
Purchase #4	$220.43	13.746%	$250.7303	$250.73	$250.75	$250.70
Purchase #5	$72.28	8.461%	$78.3956	$78.40	$78.40	$78.40
Purchase #6	$58.69	9.452%	$64.2374	$64.24	$64.25	$64.20
Purchase #7	$117.29	8.798%	$127.6092	$127.61	$127.60	$127.60
7 purchase totals =	$963.98		$1,053.5721	$1,053.58	$1,053.60	$1,053.50