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	$146.83	7.325%	$157.5853	$157.59	$157.60	$157.60
Purchase #2	$244.69	7.362%	$262.7041	$262.70	$262.70	$262.70
Purchase #3	$41.26	12.712%	$46.505	$46.51	$46.50	$46.50
Purchase #4	$213.42	4.467%	$222.9535	$222.95	$222.95	$223.00
Purchase #5	$152.61	10.534%	$168.6859	$168.69	$168.70	$168.70
Purchase #6	$157.63	6.830%	$168.3961	$168.40	$168.40	$168.40
Purchase #7	$217.25	9.677%	$238.2733	$238.27	$238.25	$238.30
7 purchase totals =	$1,173.69		$1,265.1032	$1,265.11	$1,265.10	$1,265.20