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	$32.69	5.452%	$34.4723	$34.47	$34.45	$34.50
Purchase #2	$164.37	5.705%	$173.7473	$173.75	$173.75	$173.70
Purchase #3	$240.84	7.256%	$258.3154	$258.32	$258.30	$258.30
Purchase #4	$185.46	8.543%	$201.3038	$201.30	$201.30	$201.30
Purchase #5	$89.89	13.272%	$101.8202	$101.82	$101.80	$101.80
Purchase #6	$174.26	7.584%	$187.4759	$187.48	$187.50	$187.50
Purchase #7	$82.59	9.280%	$90.2544	$90.25	$90.25	$90.30
7 purchase totals =	$970.10		$1,047.3893	$1,047.39	$1,047.35	$1,047.40