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	$151.26	13.826%	$172.1732	$172.17	$172.15	$172.20
Purchase #2	$158.97	3.368%	$164.3241	$164.32	$164.30	$164.30
Purchase #3	$56.76	9.208%	$61.9865	$61.99	$62.00	$62.00
Purchase #4	$74.84	7.154%	$80.1941	$80.19	$80.20	$80.20
Purchase #5	$153.92	6.651%	$164.1572	$164.16	$164.15	$164.20
Purchase #6	$153.97	10.599%	$170.2893	$170.29	$170.30	$170.30
Purchase #7	$213.56	9.238%	$233.2887	$233.29	$233.30	$233.30
7 purchase totals =	$963.28		$1,046.4131	$1,046.41	$1,046.40	$1,046.50