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	$109.84	4.496%	$114.7784	$114.78	$114.80	$114.80
Purchase #2	$179.58	3.746%	$186.3071	$186.31	$186.30	$186.30
Purchase #3	$89.34	10.642%	$98.8476	$98.85	$98.85	$98.80
Purchase #4	$232.49	10.479%	$256.8526	$256.85	$256.85	$256.90
Purchase #5	$64.62	11.804%	$72.2477	$72.25	$72.25	$72.20
Purchase #6	$155.74	5.354%	$164.0783	$164.08	$164.10	$164.10
Purchase #7	$153.76	3.678%	$159.4153	$159.42	$159.40	$159.40
7 purchase totals =	$985.37		$1,052.5270	$1,052.54	$1,052.55	$1,052.50