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	$174.33	4.610%	$182.3666	$182.37	$182.35	$182.40
Purchase #2	$13.55	3.190%	$13.9822	$13.98	$14.00	$14.00
Purchase #3	$64.40	4.832%	$67.5118	$67.51	$67.50	$67.50
Purchase #4	$50.40	8.533%	$54.7006	$54.70	$54.70	$54.70
Purchase #5	$197.48	9.518%	$216.2761	$216.28	$216.30	$216.30
Purchase #6	$33.48	5.595%	$35.3532	$35.35	$35.35	$35.40
Purchase #7	$178.37	10.400%	$196.9205	$196.92	$196.90	$196.90
7 purchase totals =	$712.01		$767.1110	$767.11	$767.10	$767.20