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	$92.88	10.107%	$102.2674	$102.27	$102.25	$102.30
Purchase #2	$181.29	6.431%	$192.9488	$192.95	$192.95	$192.90
Purchase #3	$141.56	3.224%	$146.1239	$146.12	$146.10	$146.10
Purchase #4	$210.69	3.161%	$217.3499	$217.35	$217.35	$217.30
Purchase #5	$91.67	13.457%	$104.006	$104.01	$104.00	$104.00
Purchase #6	$214.27	4.112%	$223.0808	$223.08	$223.10	$223.10
Purchase #7	$82.56	3.706%	$85.6197	$85.62	$85.60	$85.60
7 purchase totals =	$1,014.92		$1,071.3965	$1,071.40	$1,071.35	$1,071.30