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	$191.62	13.470%	$217.4312	$217.43	$217.45	$217.40
Purchase #2	$123.93	5.335%	$130.5417	$130.54	$130.55	$130.50
Purchase #3	$124.88	12.462%	$140.4425	$140.44	$140.45	$140.40
Purchase #4	$5.79	8.171%	$6.2631	$6.26	$6.25	$6.30
Purchase #5	$179.62	9.370%	$196.4504	$196.45	$196.45	$196.50
Purchase #6	$186.41	11.697%	$208.2144	$208.21	$208.20	$208.20
Purchase #7	$180.29	3.526%	$186.647	$186.65	$186.65	$186.60
7 purchase totals =	$992.54		$1,085.9903	$1,085.98	$1,086.00	$1,085.90