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	$157.45	3.165%	$162.4333	$162.43	$162.45	$162.40
Purchase #2	$164.51	5.834%	$174.1075	$174.11	$174.10	$174.10
Purchase #3	$200.65	6.599%	$213.8909	$213.89	$213.90	$213.90
Purchase #4	$133.72	11.454%	$149.0363	$149.04	$149.05	$149.00
Purchase #5	$135.41	9.306%	$148.0113	$148.01	$148.00	$148.00
Purchase #6	$131.47	8.402%	$142.5161	$142.52	$142.50	$142.50
Purchase #7	$139.40	10.461%	$153.9826	$153.98	$154.00	$154.00
7 purchase totals =	$1,062.61		$1,143.9780	$1,143.98	$1,144.00	$1,143.90