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	$130.29	9.418%	$142.5607	$142.56	$142.55	$142.60
Purchase #2	$73.30	4.511%	$76.6066	$76.61	$76.60	$76.60
Purchase #3	$120.70	5.685%	$127.5618	$127.56	$127.55	$127.60
Purchase #4	$28.74	13.307%	$32.5644	$32.56	$32.55	$32.60
Purchase #5	$99.35	6.778%	$106.0839	$106.08	$106.10	$106.10
Purchase #6	$246.30	12.415%	$276.8781	$276.88	$276.90	$276.90
Purchase #7	$238.30	10.640%	$263.6551	$263.66	$263.65	$263.70
7 purchase totals =	$936.98		$1,025.9106	$1,025.91	$1,025.90	$1,026.10