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	$190.36	3.508%	$197.0378	$197.04	$197.05	$197.00
Purchase #2	$17.89	5.402%	$18.8564	$18.86	$18.85	$18.90
Purchase #3	$144.70	13.661%	$164.4675	$164.47	$164.45	$164.50
Purchase #4	$45.45	3.657%	$47.1121	$47.11	$47.10	$47.10
Purchase #5	$236.71	6.368%	$251.7837	$251.78	$251.80	$251.80
Purchase #6	$205.69	13.531%	$233.5219	$233.52	$233.50	$233.50
Purchase #7	$121.44	4.851%	$127.3311	$127.33	$127.35	$127.30
7 purchase totals =	$962.24		$1,040.1105	$1,040.11	$1,040.10	$1,040.10