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	$183.85	3.419%	$190.1358	$190.14	$190.15	$190.10
Purchase #2	$145.30	3.445%	$150.3056	$150.31	$150.30	$150.30
Purchase #3	$135.85	3.310%	$140.3466	$140.35	$140.35	$140.30
Purchase #4	$182.56	10.539%	$201.8	$201.80	$201.80	$201.80
Purchase #5	$39.61	8.802%	$43.0965	$43.10	$43.10	$43.10
Purchase #6	$175.36	7.786%	$189.0135	$189.01	$189.00	$189.00
Purchase #7	$182.85	4.406%	$190.9064	$190.91	$190.90	$190.90
7 purchase totals =	$1,045.38		$1,105.6044	$1,105.62	$1,105.60	$1,105.50