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	$216.25	3.295%	$223.3754	$223.38	$223.40	$223.40
Purchase #2	$5.29	11.805%	$5.9145	$5.91	$5.90	$5.90
Purchase #3	$189.84	7.711%	$204.4786	$204.48	$204.50	$204.50
Purchase #4	$159.98	4.608%	$167.3519	$167.35	$167.35	$167.40
Purchase #5	$178.65	5.848%	$189.0975	$189.10	$189.10	$189.10
Purchase #6	$84.97	5.367%	$89.5303	$89.53	$89.55	$89.50
Purchase #7	$116.55	10.160%	$128.3915	$128.39	$128.40	$128.40
7 purchase totals =	$951.53		$1,008.1397	$1,008.14	$1,008.20	$1,008.20