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	$82.98	4.575%	$86.7763	$86.78	$86.80	$86.80
Purchase #2	$189.49	12.456%	$213.0929	$213.09	$213.10	$213.10
Purchase #3	$150.45	4.387%	$157.0502	$157.05	$157.05	$157.10
Purchase #4	$58.39	12.304%	$65.5743	$65.57	$65.55	$65.60
Purchase #5	$90.57	9.663%	$99.3218	$99.32	$99.30	$99.30
Purchase #6	$197.51	12.768%	$222.7281	$222.73	$222.75	$222.70
Purchase #7	$220.72	13.683%	$250.9211	$250.92	$250.90	$250.90
7 purchase totals =	$990.11		$1,095.4647	$1,095.46	$1,095.45	$1,095.50