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	$175.47	5.680%	$185.4367	$185.44	$185.45	$185.40
Purchase #2	$55.93	9.223%	$61.0884	$61.09	$61.10	$61.10
Purchase #3	$147.99	4.737%	$155.0003	$155.00	$155.00	$155.00
Purchase #4	$189.56	3.763%	$196.6931	$196.69	$196.70	$196.70
Purchase #5	$213.47	5.533%	$225.2813	$225.28	$225.30	$225.30
Purchase #6	$170.31	12.439%	$191.4949	$191.49	$191.50	$191.50
Purchase #7	$66.35	4.852%	$69.5693	$69.57	$69.55	$69.60
7 purchase totals =	$1,019.08		$1,084.5640	$1,084.56	$1,084.60	$1,084.60