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	$151.32	6.441%	$161.0665	$161.07	$161.05	$161.10
Purchase #2	$213.93	7.163%	$229.2538	$229.25	$229.25	$229.30
Purchase #3	$89.79	5.755%	$94.9574	$94.96	$94.95	$95.00
Purchase #4	$90.71	6.343%	$96.4637	$96.46	$96.45	$96.50
Purchase #5	$119.68	10.165%	$131.8455	$131.85	$131.85	$131.80
Purchase #6	$250.85	6.494%	$267.1402	$267.14	$267.15	$267.10
Purchase #7	$18.89	3.524%	$19.5557	$19.56	$19.55	$19.60
7 purchase totals =	$935.17		$1,000.2828	$1,000.29	$1,000.25	$1,000.40