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	$192.94	3.623%	$199.9302	$199.93	$199.95	$199.90
Purchase #2	$159.75	6.108%	$169.5075	$169.51	$169.50	$169.50
Purchase #3	$6.51	10.170%	$7.1721	$7.17	$7.15	$7.20
Purchase #4	$139.71	9.182%	$152.5382	$152.54	$152.55	$152.50
Purchase #5	$114.43	7.858%	$123.4219	$123.42	$123.40	$123.40
Purchase #6	$236.91	13.167%	$268.1039	$268.10	$268.10	$268.10
Purchase #7	$205.41	9.363%	$224.6425	$224.64	$224.65	$224.60
7 purchase totals =	$1,055.66		$1,145.3163	$1,145.31	$1,145.30	$1,145.20