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	$59.77	4.358%	$62.3748	$62.37	$62.35	$62.40
Purchase #2	$240.58	6.577%	$256.4029	$256.40	$256.40	$256.40
Purchase #3	$56.54	4.556%	$59.116	$59.12	$59.10	$59.10
Purchase #4	$82.45	6.226%	$87.5833	$87.58	$87.60	$87.60
Purchase #5	$130.44	3.811%	$135.4111	$135.41	$135.40	$135.40
Purchase #6	$123.51	6.523%	$131.5666	$131.57	$131.55	$131.60
Purchase #7	$19.48	6.616%	$20.7688	$20.77	$20.75	$20.80
7 purchase totals =	$712.77		$753.2235	$753.22	$753.15	$753.30