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	$174.52	11.652%	$194.8551	$194.86	$194.85	$194.90
Purchase #2	$105.56	3.529%	$109.2852	$109.29	$109.30	$109.30
Purchase #3	$63.83	12.161%	$71.5924	$71.59	$71.60	$71.60
Purchase #4	$85.59	13.136%	$96.8331	$96.83	$96.85	$96.80
Purchase #5	$160.65	9.790%	$176.3776	$176.38	$176.40	$176.40
Purchase #6	$160.74	12.443%	$180.7409	$180.74	$180.75	$180.70
Purchase #7	$101.56	13.723%	$115.4971	$115.50	$115.50	$115.50
7 purchase totals =	$852.45		$945.1814	$945.19	$945.25	$945.20