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	$158.36	3.837%	$164.4363	$164.44	$164.45	$164.40
Purchase #2	$29.35	12.152%	$32.9166	$32.92	$32.90	$32.90
Purchase #3	$245.32	8.435%	$266.0127	$266.01	$266.00	$266.00
Purchase #4	$244.75	12.616%	$275.6277	$275.63	$275.65	$275.60
Purchase #5	$11.75	11.424%	$13.0923	$13.09	$13.10	$13.10
Purchase #6	$215.95	11.826%	$241.4882	$241.49	$241.50	$241.50
Purchase #7	$31.34	3.628%	$32.477	$32.48	$32.50	$32.50
7 purchase totals =	$936.82		$1,026.0508	$1,026.06	$1,026.10	$1,026.00