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	$118.44	7.778%	$127.6523	$127.65	$127.65	$127.70
Purchase #2	$151.58	10.462%	$167.4383	$167.44	$167.45	$167.40
Purchase #3	$65.41	3.636%	$67.7883	$67.79	$67.80	$67.80
Purchase #4	$189.68	12.588%	$213.5569	$213.56	$213.55	$213.60
Purchase #5	$146.36	10.591%	$161.861	$161.86	$161.85	$161.90
Purchase #6	$118.94	8.366%	$128.8905	$128.89	$128.90	$128.90
Purchase #7	$165.92	7.584%	$178.5034	$178.50	$178.50	$178.50
7 purchase totals =	$956.33		$1,045.6907	$1,045.69	$1,045.70	$1,045.80