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	$134.86	7.754%	$145.317	$145.32	$145.30	$145.30
Purchase #2	$61.30	4.646%	$64.148	$64.15	$64.15	$64.10
Purchase #3	$195.86	11.835%	$219.04	$219.04	$219.05	$219.00
Purchase #4	$250.38	10.545%	$276.7826	$276.78	$276.80	$276.80
Purchase #5	$62.51	5.612%	$66.0181	$66.02	$66.00	$66.00
Purchase #6	$82.50	9.519%	$90.3532	$90.35	$90.35	$90.40
Purchase #7	$137.73	11.264%	$153.2439	$153.24	$153.25	$153.20
7 purchase totals =	$925.14		$1,014.9028	$1,014.90	$1,014.90	$1,014.80