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	$131.90	7.133%	$141.3084	$141.31	$141.30	$141.30
Purchase #2	$101.86	13.741%	$115.8566	$115.86	$115.85	$115.90
Purchase #3	$172.80	11.557%	$192.7705	$192.77	$192.75	$192.80
Purchase #4	$159.52	13.831%	$181.5832	$181.58	$181.60	$181.60
Purchase #5	$116.40	7.515%	$125.1475	$125.15	$125.15	$125.10
Purchase #6	$99.32	6.258%	$105.5354	$105.54	$105.55	$105.50
Purchase #7	$148.96	9.292%	$162.8014	$162.80	$162.80	$162.80
7 purchase totals =	$930.76		$1,025.0030	$1,025.01	$1,025.00	$1,025.00