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	$197.87	4.735%	$207.2391	$207.24	$207.25	$207.20
Purchase #2	$200.73	11.153%	$223.1174	$223.12	$223.10	$223.10
Purchase #3	$20.30	3.533%	$21.0172	$21.02	$21.00	$21.00
Purchase #4	$94.69	7.835%	$102.109	$102.11	$102.10	$102.10
Purchase #5	$18.27	12.506%	$20.5548	$20.55	$20.55	$20.60
Purchase #6	$80.28	7.631%	$86.4062	$86.41	$86.40	$86.40
Purchase #7	$118.71	4.220%	$123.7196	$123.72	$123.70	$123.70
7 purchase totals =	$730.85		$784.1633	$784.17	$784.10	$784.10