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	$220.43	7.705%	$237.4141	$237.41	$237.40	$237.40
Purchase #2	$172.38	10.842%	$191.0694	$191.07	$191.05	$191.10
Purchase #3	$57.69	3.250%	$59.5649	$59.56	$59.55	$59.60
Purchase #4	$244.48	9.723%	$268.2508	$268.25	$268.25	$268.30
Purchase #5	$61.41	9.269%	$67.1021	$67.10	$67.10	$67.10
Purchase #6	$38.68	4.779%	$40.5285	$40.53	$40.55	$40.50
Purchase #7	$155.85	3.337%	$161.0507	$161.05	$161.05	$161.10
7 purchase totals =	$950.92		$1,024.9805	$1,024.97	$1,024.95	$1,025.10