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	$222.73	8.335%	$241.2945	$241.29	$241.30	$241.30
Purchase #2	$216.88	6.206%	$230.3396	$230.34	$230.35	$230.30
Purchase #3	$81.88	9.440%	$89.6095	$89.61	$89.60	$89.60
Purchase #4	$178.83	12.288%	$200.8046	$200.80	$200.80	$200.80
Purchase #5	$86.63	6.707%	$92.4403	$92.44	$92.45	$92.40
Purchase #6	$58.76	10.616%	$64.998	$65.00	$65.00	$65.00
Purchase #7	$168.67	3.551%	$174.6595	$174.66	$174.65	$174.70
7 purchase totals =	$1,014.38		$1,094.1460	$1,094.14	$1,094.15	$1,094.10