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	$37.60	11.476%	$41.915	$41.92	$41.90	$41.90
Purchase #2	$119.95	4.838%	$125.7532	$125.75	$125.75	$125.80
Purchase #3	$172.29	11.657%	$192.3738	$192.37	$192.35	$192.40
Purchase #4	$154.91	11.616%	$172.9043	$172.90	$172.90	$172.90
Purchase #5	$209.26	3.768%	$217.1449	$217.14	$217.15	$217.10
Purchase #6	$223.77	11.542%	$249.5975	$249.60	$249.60	$249.60
Purchase #7	$124.56	3.481%	$128.8959	$128.90	$128.90	$128.90
7 purchase totals =	$1,042.34		$1,128.5846	$1,128.58	$1,128.55	$1,128.60