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	$184.81	11.226%	$205.5568	$205.56	$205.55	$205.60
Purchase #2	$72.79	12.580%	$81.947	$81.95	$81.95	$81.90
Purchase #3	$71.36	9.314%	$78.0065	$78.01	$78.00	$78.00
Purchase #4	$70.87	5.275%	$74.6084	$74.61	$74.60	$74.60
Purchase #5	$102.41	7.294%	$109.8798	$109.88	$109.90	$109.90
Purchase #6	$190.49	4.155%	$198.4049	$198.40	$198.40	$198.40
Purchase #7	$248.92	5.319%	$262.1601	$262.16	$262.15	$262.20
7 purchase totals =	$941.65		$1,010.5635	$1,010.57	$1,010.55	$1,010.60