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	$176.75	10.165%	$194.7166	$194.72	$194.70	$194.70
Purchase #2	$140.93	10.705%	$156.0166	$156.02	$156.00	$156.00
Purchase #3	$201.73	5.776%	$213.3819	$213.38	$213.40	$213.40
Purchase #4	$39.91	3.622%	$41.3555	$41.36	$41.35	$41.40
Purchase #5	$155.92	3.183%	$160.8829	$160.88	$160.90	$160.90
Purchase #6	$159.30	13.824%	$181.3216	$181.32	$181.30	$181.30
Purchase #7	$141.59	5.165%	$148.9031	$148.90	$148.90	$148.90
7 purchase totals =	$1,016.13		$1,096.5782	$1,096.58	$1,096.55	$1,096.60