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	$209.33	10.862%	$232.0674	$232.07	$232.05	$232.10
Purchase #2	$221.37	8.443%	$240.0603	$240.06	$240.05	$240.10
Purchase #3	$97.92	8.319%	$106.066	$106.07	$106.05	$106.10
Purchase #4	$119.28	10.161%	$131.4	$131.40	$131.40	$131.40
Purchase #5	$249.93	10.403%	$275.9302	$275.93	$275.95	$275.90
Purchase #6	$110.76	11.567%	$123.5716	$123.57	$123.55	$123.60
Purchase #7	$81.34	10.441%	$89.8327	$89.83	$89.85	$89.80
7 purchase totals =	$1,089.93		$1,198.9282	$1,198.93	$1,198.90	$1,199.00