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	$87.95	5.121%	$92.4539	$92.45	$92.45	$92.50
Purchase #2	$201.63	10.637%	$223.0774	$223.08	$223.10	$223.10
Purchase #3	$118.56	7.237%	$127.1402	$127.14	$127.15	$127.10
Purchase #4	$73.58	13.159%	$83.2624	$83.26	$83.25	$83.30
Purchase #5	$78.92	8.375%	$85.5296	$85.53	$85.55	$85.50
Purchase #6	$231.76	7.796%	$249.828	$249.83	$249.85	$249.80
Purchase #7	$12.53	12.150%	$14.0524	$14.05	$14.05	$14.10
7 purchase totals =	$804.93		$875.3439	$875.34	$875.40	$875.40