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	$224.65	7.516%	$241.5347	$241.53	$241.55	$241.50
Purchase #2	$64.38	3.547%	$66.6636	$66.66	$66.65	$66.70
Purchase #3	$143.65	13.174%	$162.5745	$162.57	$162.55	$162.60
Purchase #4	$123.79	10.598%	$136.9093	$136.91	$136.90	$136.90
Purchase #5	$79.27	9.660%	$86.9275	$86.93	$86.95	$86.90
Purchase #6	$156.32	5.499%	$164.916	$164.92	$164.90	$164.90
Purchase #7	$186.76	8.116%	$201.9174	$201.92	$201.90	$201.90
7 purchase totals =	$978.82		$1,061.4430	$1,061.44	$1,061.40	$1,061.40