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	$84.32	11.161%	$93.731	$93.73	$93.75	$93.70
Purchase #2	$65.84	8.801%	$71.6346	$71.63	$71.65	$71.60
Purchase #3	$73.59	11.643%	$82.1581	$82.16	$82.15	$82.20
Purchase #4	$248.49	12.531%	$279.6283	$279.63	$279.65	$279.60
Purchase #5	$82.72	13.570%	$93.9451	$93.95	$93.95	$93.90
Purchase #6	$181.81	8.679%	$197.5893	$197.59	$197.60	$197.60
Purchase #7	$178.33	10.105%	$196.3502	$196.35	$196.35	$196.40
7 purchase totals =	$915.10		$1,015.0366	$1,015.04	$1,015.10	$1,015.00