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	$181.99	6.533%	$193.8794	$193.88	$193.90	$193.90
Purchase #2	$34.44	9.137%	$37.5868	$37.59	$37.60	$37.60
Purchase #3	$95.33	9.458%	$104.3463	$104.35	$104.35	$104.30
Purchase #4	$197.56	13.342%	$223.9185	$223.92	$223.90	$223.90
Purchase #5	$182.61	5.422%	$192.5111	$192.51	$192.50	$192.50
Purchase #6	$184.54	8.869%	$200.9069	$200.91	$200.90	$200.90
Purchase #7	$142.74	11.472%	$159.1151	$159.12	$159.10	$159.10
7 purchase totals =	$1,019.21		$1,112.2641	$1,112.28	$1,112.25	$1,112.20