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	$92.55	4.373%	$96.5972	$96.60	$96.60	$96.60
Purchase #2	$66.90	9.558%	$73.2943	$73.29	$73.30	$73.30
Purchase #3	$181.55	7.668%	$195.4713	$195.47	$195.45	$195.50
Purchase #4	$229.76	7.391%	$246.7416	$246.74	$246.75	$246.70
Purchase #5	$42.91	6.133%	$45.5417	$45.54	$45.55	$45.50
Purchase #6	$150.55	5.209%	$158.3921	$158.39	$158.40	$158.40
Purchase #7	$187.33	8.513%	$203.2774	$203.28	$203.30	$203.30
7 purchase totals =	$951.55		$1,019.3156	$1,019.31	$1,019.35	$1,019.30