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	$47.51	11.550%	$52.9974	$53.00	$53.00	$53.00
Purchase #2	$150.53	13.645%	$171.0698	$171.07	$171.05	$171.10
Purchase #3	$81.61	8.288%	$88.3738	$88.37	$88.35	$88.40
Purchase #4	$133.41	6.315%	$141.8348	$141.83	$141.85	$141.80
Purchase #5	$165.40	3.655%	$171.4454	$171.45	$171.45	$171.40
Purchase #6	$194.84	12.696%	$219.5769	$219.58	$219.60	$219.60
Purchase #7	$158.61	12.280%	$178.0873	$178.09	$178.10	$178.10
7 purchase totals =	$931.91		$1,023.3854	$1,023.39	$1,023.40	$1,023.40