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	$219.96	10.693%	$243.4803	$243.48	$243.50	$243.50
Purchase #2	$12.29	9.178%	$13.418	$13.42	$13.40	$13.40
Purchase #3	$237.28	12.800%	$267.6518	$267.65	$267.65	$267.70
Purchase #4	$31.29	12.239%	$35.1196	$35.12	$35.10	$35.10
Purchase #5	$96.45	9.249%	$105.3707	$105.37	$105.35	$105.40
Purchase #6	$139.84	10.464%	$154.4729	$154.47	$154.45	$154.50
Purchase #7	$234.43	11.518%	$261.4316	$261.43	$261.45	$261.40
7 purchase totals =	$971.54		$1,080.9449	$1,080.94	$1,080.90	$1,081.00