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	$219.53	6.110%	$232.9433	$232.94	$232.95	$232.90
Purchase #2	$38.86	4.133%	$40.4661	$40.47	$40.45	$40.50
Purchase #3	$118.70	10.582%	$131.2608	$131.26	$131.25	$131.30
Purchase #4	$207.91	5.727%	$219.817	$219.82	$219.80	$219.80
Purchase #5	$54.96	8.506%	$59.6349	$59.63	$59.65	$59.60
Purchase #6	$71.32	13.137%	$80.6893	$80.69	$80.70	$80.70
Purchase #7	$181.58	8.153%	$196.3842	$196.38	$196.40	$196.40
7 purchase totals =	$892.86		$961.1956	$961.19	$961.20	$961.20