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	$249.76	4.415%	$260.7869	$260.79	$260.80	$260.80
Purchase #2	$146.60	10.518%	$162.0194	$162.02	$162.00	$162.00
Purchase #3	$143.64	9.326%	$157.0359	$157.04	$157.05	$157.00
Purchase #4	$157.32	4.233%	$163.9794	$163.98	$164.00	$164.00
Purchase #5	$54.41	9.269%	$59.4533	$59.45	$59.45	$59.50
Purchase #6	$154.45	6.427%	$164.3765	$164.38	$164.40	$164.40
Purchase #7	$54.99	4.488%	$57.458	$57.46	$57.45	$57.50
7 purchase totals =	$961.17		$1,025.1094	$1,025.12	$1,025.15	$1,025.20