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	$226.84	6.612%	$241.8387	$241.84	$241.85	$241.80
Purchase #2	$219.90	3.740%	$228.1243	$228.12	$228.10	$228.10
Purchase #3	$20.63	8.828%	$22.4512	$22.45	$22.45	$22.50
Purchase #4	$141.34	6.478%	$150.496	$150.50	$150.50	$150.50
Purchase #5	$244.61	12.668%	$275.5972	$275.60	$275.60	$275.60
Purchase #6	$146.34	4.668%	$153.1712	$153.17	$153.15	$153.20
Purchase #7	$35.67	10.271%	$39.3337	$39.33	$39.35	$39.30
7 purchase totals =	$1,035.33		$1,111.0123	$1,111.01	$1,111.00	$1,111.00