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	$146.98	10.216%	$161.9955	$162.00	$162.00	$162.00
Purchase #2	$89.72	3.555%	$92.9095	$92.91	$92.90	$92.90
Purchase #3	$113.98	13.121%	$128.9353	$128.94	$128.95	$128.90
Purchase #4	$111.29	4.545%	$116.3481	$116.35	$116.35	$116.30
Purchase #5	$135.41	9.597%	$148.4053	$148.41	$148.40	$148.40
Purchase #6	$230.31	13.787%	$262.0628	$262.06	$262.05	$262.10
Purchase #7	$89.50	10.728%	$99.1016	$99.10	$99.10	$99.10
7 purchase totals =	$917.19		$1,009.7581	$1,009.77	$1,009.75	$1,009.70