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	$173.76	9.599%	$190.4392	$190.44	$190.45	$190.40
Purchase #2	$167.51	6.834%	$178.9576	$178.96	$178.95	$179.00
Purchase #3	$164.91	4.153%	$171.7587	$171.76	$171.75	$171.80
Purchase #4	$33.91	11.341%	$37.7557	$37.76	$37.75	$37.80
Purchase #5	$98.97	10.651%	$109.5113	$109.51	$109.50	$109.50
Purchase #6	$216.50	8.721%	$235.381	$235.38	$235.40	$235.40
Purchase #7	$212.76	12.206%	$238.7295	$238.73	$238.75	$238.70
7 purchase totals =	$1,068.32		$1,162.5330	$1,162.54	$1,162.55	$1,162.60