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	$145.28	11.839%	$162.4797	$162.48	$162.50	$162.50
Purchase #2	$14.97	6.169%	$15.8935	$15.89	$15.90	$15.90
Purchase #3	$196.73	12.820%	$221.9508	$221.95	$221.95	$222.00
Purchase #4	$168.84	9.654%	$185.1398	$185.14	$185.15	$185.10
Purchase #5	$165.63	3.547%	$171.5049	$171.50	$171.50	$171.50
Purchase #6	$184.74	11.215%	$205.4586	$205.46	$205.45	$205.50
Purchase #7	$98.29	7.194%	$105.361	$105.36	$105.35	$105.40
7 purchase totals =	$974.48		$1,067.7883	$1,067.78	$1,067.80	$1,067.90