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	$58.75	5.500%	$61.9813	$61.98	$62.00	$62.00
Purchase #2	$199.73	11.180%	$222.0598	$222.06	$222.05	$222.10
Purchase #3	$14.78	8.488%	$16.0345	$16.03	$16.05	$16.00
Purchase #4	$250.92	3.345%	$259.3133	$259.31	$259.30	$259.30
Purchase #5	$167.83	12.776%	$189.272	$189.27	$189.25	$189.30
Purchase #6	$84.77	5.370%	$89.3221	$89.32	$89.30	$89.30
Purchase #7	$215.80	6.363%	$229.5314	$229.53	$229.55	$229.50
7 purchase totals =	$992.58		$1,067.5144	$1,067.50	$1,067.50	$1,067.50