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	$198.64	7.348%	$213.2361	$213.24	$213.25	$213.20
Purchase #2	$88.33	3.639%	$91.5443	$91.54	$91.55	$91.50
Purchase #3	$143.93	10.136%	$158.5187	$158.52	$158.50	$158.50
Purchase #4	$86.74	8.164%	$93.8215	$93.82	$93.80	$93.80
Purchase #5	$210.96	13.724%	$239.9122	$239.91	$239.90	$239.90
Purchase #6	$164.37	4.343%	$171.5086	$171.51	$171.50	$171.50
Purchase #7	$181.51	13.404%	$205.8396	$205.84	$205.85	$205.80
7 purchase totals =	$1,074.48		$1,174.3810	$1,174.38	$1,174.35	$1,174.20