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	$188.78	13.235%	$213.765	$213.77	$213.75	$213.80
Purchase #2	$168.82	12.248%	$189.4971	$189.50	$189.50	$189.50
Purchase #3	$237.80	3.128%	$245.2384	$245.24	$245.25	$245.20
Purchase #4	$246.74	11.619%	$275.4087	$275.41	$275.40	$275.40
Purchase #5	$153.53	13.866%	$174.8185	$174.82	$174.80	$174.80
Purchase #6	$193.76	9.760%	$212.671	$212.67	$212.65	$212.70
Purchase #7	$81.90	9.649%	$89.8025	$89.80	$89.80	$89.80
7 purchase totals =	$1,271.33		$1,401.2012	$1,401.21	$1,401.15	$1,401.20