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	$53.35	10.776%	$59.099	$59.10	$59.10	$59.10
Purchase #2	$34.84	7.223%	$37.3565	$37.36	$37.35	$37.40
Purchase #3	$119.89	8.791%	$130.4295	$130.43	$130.45	$130.40
Purchase #4	$185.68	12.574%	$209.0274	$209.03	$209.05	$209.00
Purchase #5	$202.39	8.416%	$219.4231	$219.42	$219.40	$219.40
Purchase #6	$163.59	3.422%	$169.188	$169.19	$169.20	$169.20
Purchase #7	$197.83	12.805%	$223.1621	$223.16	$223.15	$223.20
7 purchase totals =	$957.57		$1,047.6856	$1,047.69	$1,047.70	$1,047.70