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	$91.53	4.720%	$95.8502	$95.85	$95.85	$95.90
Purchase #2	$120.31	10.670%	$133.1471	$133.15	$133.15	$133.10
Purchase #3	$96.56	5.435%	$101.808	$101.81	$101.80	$101.80
Purchase #4	$124.61	11.661%	$139.1408	$139.14	$139.15	$139.10
Purchase #5	$162.39	3.171%	$167.5394	$167.54	$167.55	$167.50
Purchase #6	$196.98	11.258%	$219.156	$219.16	$219.15	$219.20
Purchase #7	$15.61	3.307%	$16.1262	$16.13	$16.15	$16.10
7 purchase totals =	$807.99		$872.7677	$872.78	$872.80	$872.70