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	$58.47	6.617%	$62.339	$62.34	$62.35	$62.30
Purchase #2	$78.50	6.497%	$83.6001	$83.60	$83.60	$83.60
Purchase #3	$87.95	4.392%	$91.8128	$91.81	$91.80	$91.80
Purchase #4	$124.78	13.712%	$141.8898	$141.89	$141.90	$141.90
Purchase #5	$115.81	11.487%	$129.1131	$129.11	$129.10	$129.10
Purchase #6	$188.37	4.517%	$196.8787	$196.88	$196.90	$196.90
Purchase #7	$51.49	9.741%	$56.5056	$56.51	$56.50	$56.50
7 purchase totals =	$705.37		$762.1391	$762.14	$762.15	$762.10