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	$73.64	5.461%	$77.6615	$77.66	$77.65	$77.70
Purchase #2	$86.39	4.539%	$90.3112	$90.31	$90.30	$90.30
Purchase #3	$147.59	4.357%	$154.0205	$154.02	$154.00	$154.00
Purchase #4	$175.67	7.149%	$188.2286	$188.23	$188.25	$188.20
Purchase #5	$221.63	7.306%	$237.8223	$237.82	$237.80	$237.80
Purchase #6	$195.70	13.767%	$222.642	$222.64	$222.65	$222.60
Purchase #7	$54.75	12.275%	$61.4706	$61.47	$61.45	$61.50
7 purchase totals =	$955.37		$1,032.1567	$1,032.15	$1,032.10	$1,032.10