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	$68.43	4.281%	$71.3595	$71.36	$71.35	$71.40
Purchase #2	$191.96	13.461%	$217.7997	$217.80	$217.80	$217.80
Purchase #3	$110.68	3.727%	$114.805	$114.81	$114.80	$114.80
Purchase #4	$189.65	3.689%	$196.6462	$196.65	$196.65	$196.60
Purchase #5	$143.84	6.426%	$153.0832	$153.08	$153.10	$153.10
Purchase #6	$192.29	8.808%	$209.2269	$209.23	$209.25	$209.20
Purchase #7	$81.53	10.565%	$90.1436	$90.14	$90.15	$90.10
7 purchase totals =	$978.38		$1,053.0641	$1,053.07	$1,053.10	$1,053.00