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	$35.77	5.810%	$37.8482	$37.85	$37.85	$37.80
Purchase #2	$67.98	6.612%	$72.4748	$72.47	$72.45	$72.50
Purchase #3	$73.79	6.650%	$78.697	$78.70	$78.70	$78.70
Purchase #4	$25.44	3.738%	$26.3909	$26.39	$26.40	$26.40
Purchase #5	$207.82	10.500%	$229.6411	$229.64	$229.65	$229.60
Purchase #6	$234.26	9.852%	$257.3393	$257.34	$257.35	$257.30
Purchase #7	$168.69	3.443%	$174.498	$174.50	$174.50	$174.50
7 purchase totals =	$813.75		$876.8893	$876.89	$876.90	$876.80