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	$195.31	10.656%	$216.1222	$216.12	$216.10	$216.10
Purchase #2	$37.72	13.535%	$42.8254	$42.83	$42.85	$42.80
Purchase #3	$29.67	5.336%	$31.2532	$31.25	$31.25	$31.30
Purchase #4	$224.98	11.129%	$250.018	$250.02	$250.00	$250.00
Purchase #5	$76.93	13.268%	$87.1371	$87.14	$87.15	$87.10
Purchase #6	$122.82	7.456%	$131.9775	$131.98	$132.00	$132.00
Purchase #7	$248.28	10.174%	$273.54	$273.54	$273.55	$273.50
7 purchase totals =	$935.71		$1,032.8734	$1,032.88	$1,032.90	$1,032.80