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	$98.34	11.188%	$109.3423	$109.34	$109.35	$109.30
Purchase #2	$151.96	12.725%	$171.2969	$171.30	$171.30	$171.30
Purchase #3	$222.81	10.158%	$245.443	$245.44	$245.45	$245.40
Purchase #4	$205.58	13.581%	$233.4998	$233.50	$233.50	$233.50
Purchase #5	$83.39	5.402%	$87.8947	$87.89	$87.90	$87.90
Purchase #6	$219.38	10.472%	$242.3535	$242.35	$242.35	$242.40
Purchase #7	$50.70	5.679%	$53.5793	$53.58	$53.60	$53.60
7 purchase totals =	$1,032.16		$1,143.4095	$1,143.40	$1,143.45	$1,143.40