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	$175.88	4.689%	$184.127	$184.13	$184.15	$184.10
Purchase #2	$144.90	10.759%	$160.4898	$160.49	$160.50	$160.50
Purchase #3	$100.50	3.197%	$103.713	$103.71	$103.70	$103.70
Purchase #4	$80.73	10.560%	$89.2551	$89.26	$89.25	$89.30
Purchase #5	$22.58	8.160%	$24.4225	$24.42	$24.40	$24.40
Purchase #6	$248.39	6.778%	$265.2259	$265.23	$265.25	$265.20
Purchase #7	$198.59	10.166%	$218.7787	$218.78	$218.80	$218.80
7 purchase totals =	$971.57		$1,046.0120	$1,046.02	$1,046.05	$1,046.00