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	$219.65	4.782%	$230.1537	$230.15	$230.15	$230.20
Purchase #2	$153.64	7.255%	$164.7866	$164.79	$164.80	$164.80
Purchase #3	$229.61	4.598%	$240.1675	$240.17	$240.15	$240.20
Purchase #4	$114.60	3.250%	$118.3245	$118.32	$118.30	$118.30
Purchase #5	$85.44	12.201%	$95.8645	$95.86	$95.85	$95.90
Purchase #6	$167.82	8.360%	$181.8498	$181.85	$181.85	$181.80
Purchase #7	$178.42	7.127%	$191.136	$191.14	$191.15	$191.10
7 purchase totals =	$1,149.18		$1,222.2826	$1,222.28	$1,222.25	$1,222.30