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	$96.56	8.768%	$105.0264	$105.03	$105.05	$105.00
Purchase #2	$59.82	7.160%	$64.1031	$64.10	$64.10	$64.10
Purchase #3	$233.75	4.873%	$245.1406	$245.14	$245.15	$245.10
Purchase #4	$33.49	11.602%	$37.3755	$37.38	$37.40	$37.40
Purchase #5	$119.91	3.776%	$124.4378	$124.44	$124.45	$124.40
Purchase #6	$163.34	7.538%	$175.6526	$175.65	$175.65	$175.70
Purchase #7	$182.93	7.433%	$196.5272	$196.53	$196.55	$196.50
7 purchase totals =	$889.80		$948.2632	$948.27	$948.35	$948.20