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	$80.93	7.434%	$86.9463	$86.95	$86.95	$86.90
Purchase #2	$135.91	11.524%	$151.5723	$151.57	$151.55	$151.60
Purchase #3	$114.52	9.135%	$124.9814	$124.98	$125.00	$125.00
Purchase #4	$114.96	10.503%	$127.0342	$127.03	$127.05	$127.00
Purchase #5	$78.32	4.823%	$82.0974	$82.10	$82.10	$82.10
Purchase #6	$156.77	3.856%	$162.8151	$162.82	$162.80	$162.80
Purchase #7	$106.36	12.390%	$119.538	$119.54	$119.55	$119.50
7 purchase totals =	$787.77		$854.9847	$854.99	$855.00	$854.90