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	$212.70	4.572%	$222.4246	$222.42	$222.40	$222.40
Purchase #2	$174.94	7.717%	$188.4401	$188.44	$188.45	$188.40
Purchase #3	$40.94	6.653%	$43.6637	$43.66	$43.65	$43.70
Purchase #4	$233.92	4.743%	$245.0148	$245.01	$245.00	$245.00
Purchase #5	$91.57	11.696%	$102.28	$102.28	$102.30	$102.30
Purchase #6	$150.63	7.765%	$162.3264	$162.33	$162.35	$162.30
Purchase #7	$132.71	13.420%	$150.5197	$150.52	$150.50	$150.50
7 purchase totals =	$1,037.41		$1,114.6693	$1,114.66	$1,114.65	$1,114.60