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	$118.96	11.151%	$132.2252	$132.23	$132.25	$132.20
Purchase #2	$12.45	12.764%	$14.0391	$14.04	$14.05	$14.00
Purchase #3	$80.33	4.450%	$83.9047	$83.90	$83.90	$83.90
Purchase #4	$159.76	6.777%	$170.5869	$170.59	$170.60	$170.60
Purchase #5	$144.34	12.454%	$162.3161	$162.32	$162.30	$162.30
Purchase #6	$47.61	6.769%	$50.8327	$50.83	$50.85	$50.80
Purchase #7	$143.55	4.656%	$150.2337	$150.23	$150.25	$150.20
7 purchase totals =	$707.00		$764.1384	$764.14	$764.20	$764.00