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	$238.49	11.494%	$265.902	$265.90	$265.90	$265.90
Purchase #2	$164.77	4.153%	$171.6129	$171.61	$171.60	$171.60
Purchase #3	$6.58	5.687%	$6.9542	$6.95	$6.95	$7.00
Purchase #4	$203.61	11.431%	$226.8847	$226.88	$226.90	$226.90
Purchase #5	$93.93	3.206%	$96.9414	$96.94	$96.95	$96.90
Purchase #6	$61.40	10.625%	$67.9238	$67.92	$67.90	$67.90
Purchase #7	$186.45	5.413%	$196.5425	$196.54	$196.55	$196.50
7 purchase totals =	$955.23		$1,032.7615	$1,032.74	$1,032.75	$1,032.70