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	$162.48	7.465%	$174.6091	$174.61	$174.60	$174.60
Purchase #2	$123.25	3.435%	$127.4836	$127.48	$127.50	$127.50
Purchase #3	$190.83	9.760%	$209.455	$209.46	$209.45	$209.50
Purchase #4	$9.64	11.328%	$10.732	$10.73	$10.75	$10.70
Purchase #5	$202.41	3.195%	$208.877	$208.88	$208.90	$208.90
Purchase #6	$96.66	12.232%	$108.4835	$108.48	$108.50	$108.50
Purchase #7	$158.93	3.460%	$164.429	$164.43	$164.45	$164.40
7 purchase totals =	$944.20		$1,004.0692	$1,004.07	$1,004.15	$1,004.10