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	$84.83	13.252%	$96.0717	$96.07	$96.05	$96.10
Purchase #2	$197.59	13.191%	$223.6541	$223.65	$223.65	$223.70
Purchase #3	$53.73	13.728%	$61.1061	$61.11	$61.10	$61.10
Purchase #4	$131.63	4.406%	$137.4296	$137.43	$137.45	$137.40
Purchase #5	$127.34	4.456%	$133.0143	$133.01	$133.00	$133.00
Purchase #6	$81.72	5.270%	$86.0266	$86.03	$86.05	$86.00
Purchase #7	$21.86	12.390%	$24.5685	$24.57	$24.55	$24.60
7 purchase totals =	$698.70		$761.8709	$761.87	$761.85	$761.90