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	$212.49	9.822%	$233.3608	$233.36	$233.35	$233.40
Purchase #2	$31.70	5.584%	$33.4701	$33.47	$33.45	$33.50
Purchase #3	$110.57	7.364%	$118.7124	$118.71	$118.70	$118.70
Purchase #4	$163.76	11.829%	$183.1312	$183.13	$183.15	$183.10
Purchase #5	$35.61	4.159%	$37.091	$37.09	$37.10	$37.10
Purchase #6	$167.96	4.331%	$175.2343	$175.23	$175.25	$175.20
Purchase #7	$144.69	13.520%	$164.2521	$164.25	$164.25	$164.30
7 purchase totals =	$866.78		$945.2519	$945.24	$945.25	$945.30