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	$201.48	3.538%	$208.6084	$208.61	$208.60	$208.60
Purchase #2	$22.81	13.454%	$25.8789	$25.88	$25.90	$25.90
Purchase #3	$239.33	6.740%	$255.4608	$255.46	$255.45	$255.50
Purchase #4	$243.81	4.718%	$255.313	$255.31	$255.30	$255.30
Purchase #5	$174.37	5.457%	$183.8854	$183.89	$183.90	$183.90
Purchase #6	$17.55	10.524%	$19.397	$19.40	$19.40	$19.40
Purchase #7	$201.87	4.700%	$211.3579	$211.36	$211.35	$211.40
7 purchase totals =	$1,101.22		$1,159.9014	$1,159.91	$1,159.90	$1,160.00