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	$193.70	7.654%	$208.5258	$208.53	$208.55	$208.50
Purchase #2	$229.43	5.682%	$242.4662	$242.47	$242.45	$242.50
Purchase #3	$47.70	9.618%	$52.2878	$52.29	$52.30	$52.30
Purchase #4	$182.63	4.824%	$191.4401	$191.44	$191.45	$191.40
Purchase #5	$146.70	3.816%	$152.2981	$152.30	$152.30	$152.30
Purchase #6	$88.94	13.717%	$101.1399	$101.14	$101.15	$101.10
Purchase #7	$139.63	8.256%	$151.1579	$151.16	$151.15	$151.20
7 purchase totals =	$1,028.73		$1,099.3158	$1,099.33	$1,099.35	$1,099.30