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	$163.48	6.645%	$174.3432	$174.34	$174.35	$174.30
Purchase #2	$158.35	10.684%	$175.2681	$175.27	$175.25	$175.30
Purchase #3	$183.46	3.540%	$189.9545	$189.95	$189.95	$190.00
Purchase #4	$99.47	11.647%	$111.0553	$111.06	$111.05	$111.10
Purchase #5	$119.27	13.182%	$134.9922	$134.99	$135.00	$135.00
Purchase #6	$160.39	6.679%	$171.1024	$171.10	$171.10	$171.10
Purchase #7	$144.33	7.103%	$154.5818	$154.58	$154.60	$154.60
7 purchase totals =	$1,028.75		$1,111.2975	$1,111.29	$1,111.30	$1,111.40