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	$88.32	9.449%	$96.6654	$96.67	$96.65	$96.70
Purchase #2	$15.39	3.508%	$15.9299	$15.93	$15.95	$15.90
Purchase #3	$165.40	4.130%	$172.231	$172.23	$172.25	$172.20
Purchase #4	$230.32	10.775%	$255.137	$255.14	$255.15	$255.10
Purchase #5	$94.35	11.438%	$105.1418	$105.14	$105.15	$105.10
Purchase #6	$192.73	10.849%	$213.6393	$213.64	$213.65	$213.60
Purchase #7	$179.90	10.732%	$199.2069	$199.21	$199.20	$199.20
7 purchase totals =	$966.41		$1,057.9513	$1,057.96	$1,058.00	$1,057.80