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	$205.28	13.719%	$233.4424	$233.44	$233.45	$233.40
Purchase #2	$35.76	9.737%	$39.242	$39.24	$39.25	$39.20
Purchase #3	$225.75	6.362%	$240.1122	$240.11	$240.10	$240.10
Purchase #4	$49.55	3.546%	$51.307	$51.31	$51.30	$51.30
Purchase #5	$104.82	13.793%	$119.2778	$119.28	$119.30	$119.30
Purchase #6	$225.50	5.607%	$238.1438	$238.14	$238.15	$238.10
Purchase #7	$150.59	3.217%	$155.4345	$155.43	$155.45	$155.40
7 purchase totals =	$997.25		$1,076.9597	$1,076.95	$1,077.00	$1,076.80