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	$186.74	13.386%	$211.737	$211.74	$211.75	$211.70
Purchase #2	$209.97	13.633%	$238.5952	$238.60	$238.60	$238.60
Purchase #3	$206.66	10.517%	$228.3944	$228.39	$228.40	$228.40
Purchase #4	$91.56	13.246%	$103.688	$103.69	$103.70	$103.70
Purchase #5	$93.93	12.203%	$105.3923	$105.39	$105.40	$105.40
Purchase #6	$178.55	5.551%	$188.4613	$188.46	$188.45	$188.50
Purchase #7	$141.90	7.169%	$152.0728	$152.07	$152.05	$152.10
7 purchase totals =	$1,109.31		$1,228.3410	$1,228.34	$1,228.35	$1,228.40