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	$23.41	6.587%	$24.952	$24.95	$24.95	$25.00
Purchase #2	$63.65	5.857%	$67.378	$67.38	$67.40	$67.40
Purchase #3	$102.40	7.272%	$109.8465	$109.85	$109.85	$109.80
Purchase #4	$163.31	4.738%	$171.0476	$171.05	$171.05	$171.00
Purchase #5	$174.62	5.671%	$184.5227	$184.52	$184.50	$184.50
Purchase #6	$58.54	11.131%	$65.0561	$65.06	$65.05	$65.10
Purchase #7	$175.93	11.421%	$196.023	$196.02	$196.00	$196.00
7 purchase totals =	$761.86		$818.8259	$818.83	$818.80	$818.80