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	$212.92	4.385%	$222.2565	$222.26	$222.25	$222.30
Purchase #2	$210.49	7.128%	$225.4937	$225.49	$225.50	$225.50
Purchase #3	$206.57	10.558%	$228.3797	$228.38	$228.40	$228.40
Purchase #4	$23.49	8.598%	$25.5097	$25.51	$25.50	$25.50
Purchase #5	$153.35	4.298%	$159.941	$159.94	$159.95	$159.90
Purchase #6	$96.43	3.362%	$99.672	$99.67	$99.65	$99.70
Purchase #7	$160.79	6.526%	$171.2832	$171.28	$171.30	$171.30
7 purchase totals =	$1,064.04		$1,132.5358	$1,132.53	$1,132.55	$1,132.60