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	$61.79	9.663%	$67.7608	$67.76	$67.75	$67.80
Purchase #2	$243.82	7.871%	$263.0111	$263.01	$263.00	$263.00
Purchase #3	$23.62	6.585%	$25.1754	$25.18	$25.20	$25.20
Purchase #4	$136.93	9.862%	$150.434	$150.43	$150.45	$150.40
Purchase #5	$78.26	5.526%	$82.5846	$82.58	$82.60	$82.60
Purchase #6	$182.51	5.345%	$192.2652	$192.27	$192.25	$192.30
Purchase #7	$233.62	4.268%	$243.5909	$243.59	$243.60	$243.60
7 purchase totals =	$960.55		$1,024.8220	$1,024.82	$1,024.85	$1,024.90