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	$98.65	3.741%	$102.3405	$102.34	$102.35	$102.30
Purchase #2	$9.65	9.737%	$10.5896	$10.59	$10.60	$10.60
Purchase #3	$111.81	7.635%	$120.3467	$120.35	$120.35	$120.30
Purchase #4	$43.40	4.460%	$45.3356	$45.34	$45.35	$45.30
Purchase #5	$206.32	3.265%	$213.0563	$213.06	$213.05	$213.10
Purchase #6	$131.83	8.137%	$142.557	$142.56	$142.55	$142.60
Purchase #7	$159.54	7.236%	$171.0843	$171.08	$171.10	$171.10
7 purchase totals =	$761.20		$805.3100	$805.32	$805.35	$805.30